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Determinants of weight loss success with alternate day fasting
ORCP-505; No. of Pages 5
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Obesity Research & Clinical Practice (2015) xxx, xxx—xxx
SHORT REPORT
Determinants of weight loss success with alternate day fasting Krista A. Varady ∗, Kristin K. Hoddy, Cynthia M. Kroeger, John F. Trepanowski, Monica C. Klempel, Adrienne Barnosky, Surabhi Bhutani Department of Kinesiology and Nutrition, University of Illinois at Chicago, 1919 West Taylor Street, Chicago, IL, USA Received 15 July 2015 ; received in revised form 24 August 2015; accepted 30 August 2015
KEYWORDS Weight loss success; Determinants; Demographics; Body weight; Obese adults
Summary This study examined what characteristics predict weight loss success with alternate day fasting (ADF). Four 8-week trials of ADF (n = 121) were included in the analysis. Subjects aged 50—59 y achieved greater (P = 0.01) weight loss than other age groups. Males and females achieved similar weight loss. Caucasian subjects achieved greater (P = 0.03) weight loss than other races. Baseline body weight and baseline BMI did not predict degree of weight loss achieved with the diet. These findings may help clinicians to decide which population groups may benefit most from an ADF approach. © 2015 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
Introduction Alternate day fasting (ADF) is effective for weight loss. ADF involves a ‘‘fast day’’ where an individual consumes 25% of their energy needs as a lunch or dinner, alternated with a ‘‘feast day’’ where a person is permitted to eat ad libitum (with no ∗
Corresponding author at: Department of Kinesiology and Nutrition, University of Illinois at Chicago, 1919 West Taylor Street, Room 506F, Chicago, IL 60612, USA. Tel.: +1 312 996 7897; fax: +1 312 413 0319. E-mail address: [email protected] (K.A. Varady).
limitations on type or quantity of food consumed). Other forms of alternate day fasting, which involve a complete fast on the fast day (i.e. consuming water only), have also been examined. Eight shortterm ADF trials have been performed to date [1—8]. Results from these studies report body weight decreases of 3—8% after 2—12 weeks of treatment [1—8]. However, in these studies, the distribution of weight loss success varied widely. For instance, in pooling the data, we observed that ∼5% of individuals gained weight with ADF, ∼5% lost no weight, ∼25% lost <4% of weight, ∼60% lost 4—8% of weight, and ∼5% lost >8% of baseline body weight [1,3,5,6].
http://dx.doi.org/10.1016/j.orcp.2015.08.020 1871-403X/© 2015 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Varady KA, et al. Determinants of weight loss success with alternate day fasting. Obes Res Clin Pract (2015), http://dx.doi.org/10.1016/j.orcp.2015.08.020
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The reason why certain individuals respond better than others to ADF, remains unclear. Accordingly, this pilot study was undertaken to examine if certain key characteristics, namely age, sex, race/ethnicity or baseline body weight/BMI, can predict weight loss success with ADF.
Methods Study selection The data used in this analysis are from four separate 8-week trials of ADF performed by our lab group. Full details regarding subject selection, interventions, and outcome measures have been published elsewhere [1,3,5,6]. These four studies [1,3,5,6] were selected because they had similar population groups, and comparable ADF interventions in terms of study diet and trial duration. It should also be noted that, when a study employed multiple intervention arms, only the ADF diet arm (low fat or high fat background diet) was used in the analysis. For the study [1] that combined ADF plus exercise, only the ADF diet arm was used in the present analysis. Moreover, if the study duration exceeded 8 weeks, the 8-week data points were used as the final time points.
Study populations and diets Subject selection procedures were almost identical between the four studies [1,3,5,6]. In brief, subjects were recruited from the Chicago area by advertisements. Key inclusion criteria were as follows: male or female, age 25—65 y, BMI between 30 and 45 kg/m2 , weight stable, previously sedentary or lightly active, non-diabetic, non-smoker, and no history of cardiovascular disease. Experimental protocols were approved by the Office for the Protection of Research Subjects at the University of Illinois, Chicago, and all volunteers gave written informed consent. All subjects participated in an 8-week ADF protocol. During the ADF diet, subjects consumed 25% of their baseline energy needs on the fast day (24 h), and ate ad libitum on each alternating feast day (24 h).
Measures Demographic information, including age, sex, race, and ethnicity, was collected at baseline. For the present analysis, age was subcategorised as 25—29 y, 30—39 y, 40—49 y, 50—59 y, or 60—65 y. Race/ethnicity was categorised as African American, Caucasian, or Hispanic, and sex was
categorised as male or female. A total of n = 2 Asian subjects were recruited across all studies. Because this number of Asian subjects is so low, these subjects were removed from the analysis of race/ethnicity (Fig. 2A and B). There were no selfreported mixed-race or mixed-ethnicity individuals in any of the studies. Two individuals had participated in more than one study. The data for these subjects was used only once, and was removed from data sets of subsequent studies. Body weight was measured using a balance beam scale (HealthOMeter, Boca Raton, FL) at the research centre at baseline and week 8. Baseline body weight was categorised as 70—84.9 kg, 85—99.9 kg, 100—114.5 kg, or 115—129.9 kg. Baseline body mass index (BMI) was calculated as kg/m2 , and was subcategorised as 25—29.9 kg/m2 , 30—34.9 kg/m2 , 35—39.9 kg/m2 , and 40—44.9 kg/m2 . Weight loss was calculated as the absolute change in body weight between week 8 and week 0 (baseline).
Statistics Results are presented as mean ± SEM. Shapiro—Wilk tests for normality were included in the model. No variables were found to be not normal. Homogeneity of variance was tested by Levene’s test, and the variances were not statistically different from each other. A one-way ANOVA was used to test whether degree of weight loss differed between subcategories for each variable. When a significant difference was found between groups (P < 0.05), a Tukey post hoc test was performed to determine the differences between group means. Differences were considered significant at P < 0.05. All data was analysed using SPSS software (version 21.0, SPSS Inc, Chicago, IL).
Results A total of 121 subjects were included in the analysis. The degree of weight loss achieved by subjects of varying age ranges is portrayed in Fig. 1A and B. Results reveal that subjects aged 50—59.9 y achieved greater (P = 0.01) absolute and percent weight loss than subjects in other age groups. As for sex differences, there were no differences in the degree of weight loss achieved by male versus female subjects (Fig. 1C and D). Amount of weight loss achieved by subjects of varying races is displayed in Fig. 2A and B. Caucasian subjects achieved greater absolute (P = 0.03) and percent (P = 0.04) weight loss than African American and Hispanic subjects. When subjects were subcategorised by baseline body weight, there
Please cite this article in press as: Varady KA, et al. Determinants of weight loss success with alternate day fasting. Obes Res Clin Pract (2015), http://dx.doi.org/10.1016/j.orcp.2015.08.020
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Figure 1 Degree of weight loss by age group and sex. Values reported as mean ± SEM. Means not sharing a common superscript letter are significantly different at P < 0.05 based on a Tukey post hoc test. (A) Subjects aged 50—59.9 years achieved greater (P = 0.01) absolute weight loss than subjects in other age groups. (B) Subjects aged 50—59.9 years achieved greater (P = 0.01) percent weight loss than subjects in other age groups. Number of subjects: 25—29 y (n = 10), 30—39 y (n = 36), 40—49 y (n = 34), 50—59 y (n = 34), 60—65 y (n = 7). (C) No difference between females and males for absolute weight loss achieved. (D) No difference between females and males for percent weight loss achieved. Number of subjects: female (n = 107), male (n = 14).
were no differences between subcategories for absolute weight loss (Fig. 2C) or percent weight loss (Fig. 2D). Moreover, when subjects were subcategorised by baseline BMI, there were no differences between subcategories for absolute weight loss (Fig. 2E) or percent weight loss (Fig. 2F).
Discussion This is the first study to examine whether certain characteristics, namely age, sex, race/ethnicity, or baseline body weight predict weight loss success with ADF. We show here that older individuals (50—59 y) and Caucasian subjects may lose greater amounts of weight with ADF when compared to other age groups or races. Sex, baseline body weight, and baseline BMI had no impact on the degree of weight loss achieved with this diet. Our findings are in accordance with other trials showing that older individuals have more success
with dietary restriction [9—11]. Although the reason for this remains unclear, it is possible that the biology of older adults [12], and the cultural norms (i.e. being able to follow prescribed instructions more so than younger adults), predisposes them to greater weight loss [13]. It is also unclear why Caucasian subjects lost more weight with this protocol. It should be noted, however, that socioeconomic status was not measured in this study, and may confound the relationship between race and weight loss success [14,15]. Another confounding variable may be the types of foods (i.e. pizza, pasta, chicken dishes, etc.) provided to subjects during the dietary intervention periods of the studies. These diets were flawed in that they were not culturally sensitive [16], and as such, may have not been very palatable to individuals of varying cultural backgrounds. This lower palatability may have resulted in blunted adherence and weight loss. Interestingly, sex, baseline body weight, and baseline BMI had no impact on weight loss success.
Please cite this article in press as: Varady KA, et al. Determinants of weight loss success with alternate day fasting. Obes Res Clin Pract (2015), http://dx.doi.org/10.1016/j.orcp.2015.08.020
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Figure 2 Degree of weight loss by race/ethnicity, baseline body weight, and baseline BMI. Values reported as mean ± SEM. Means not sharing a common superscript letter are significantly different at P < 0.05 based on a Tukey post hoc test. (A) Caucasian subjects achieved greater (P = 0.03) absolute weight loss than African American and Hispanic subjects. (B) Caucasian subjects achieved greater (P = 0.04) percent weight loss than African American and Hispanic subjects. Number of subjects: African American (n = 65), Caucasian (n = 23), Hispanic (n = 31). (C) No difference for absolute weight loss when subjects were subcategorised by baseline body weight. (D) No difference for percent weight loss when subjects were subcategorised by baseline body weight. Number of subjects: 70—84 kg (n = 37), 85—99 kg (n = 49), 100—114 kg (n = 30), 115—129 kg (n = 5). (E) No difference for absolute weight loss when subjects were subcategorised by baseline BMI. (F) No difference for percent weight loss when subjects were subcategorised by baseline BMI. Number of subjects: 25—29.9 kg/m2 (n = 8), 30—34.9 kg/m2 (n = 62), 35—39.9 kg/m2 (n = 45), 40—44.9 kg/m2 (n = 6).
However, since our sample was quite small (n = 121), we may have lacked the power to detect differences between subcategories of these variables. This pilot study has several limitations. First, we did not measure other key determinants of weight loss success, namely education level, marriage status, number of children, employment status, and income level. Each of these variables play important roles in an individual’s weight loss journey, and may act as confounders in the present analysis. Second, we did not perform multivariable logistic regression to assess the independent contributions of age, sex, race/ethnicity and body weight in
predicting weight loss. Third, we did not assess how social support may have affected our findings [17]. Future trials in this area should implement a comprehensive demographics questionnaire, social support scale, and regression analysis to answer these important questions. Fourth, we did not examine how subject compliance related to weight loss success. Although we measured compliance in some of our studies via food records [1,5,6], we observed that the subjects who lost little or no weight were also the subjects who did not return their records. Thus, the compliance data for these subjects is unknown. This also makes it difficult to
Please cite this article in press as: Varady KA, et al. Determinants of weight loss success with alternate day fasting. Obes Res Clin Pract (2015), http://dx.doi.org/10.1016/j.orcp.2015.08.020
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Determinants of weight loss with alternate day fasting correlate compliance with weight loss success since most of the compliance data is missing for the subjects on the lower end of the weight loss scale. For this reason, we did not include the compliance data in the present analysis. Fifth, some of the subcategories had a relatively small n in comparison to the others. This is particularly true for the ‘‘male’’ sex subcategory, ‘‘60—65 y’’ age subcategory, ‘‘115—129 kg’’ baseline body weight subcategory, and the ‘‘40—44.9 kg/m2 ’’ baseline BMI subcategory. The small number of participants in each of these subcategories may limit our power to detect differences between groups. This should be taken into consideration when interpreting these data. In summary, these preliminary findings may help clinicians to decide which population groups may benefit most from an ADF approach. These data, however, warrant confirmation in a large-scale clinical trial that addresses each of the abovementioned limitations.
Funding source Departmental funding, Kinesiology and Nutrition, University of Illinois at Chicago.
Conflict of interest Krista Varady is the author of the book ‘‘The Every Other Day Diet’’ published by the Hachette Book Group. The other authors have no competing interests to disclose.
Acknowledgements KAV designed the experiment, analysed the data, and wrote the manuscript. KKH, CMK, JFT, MCK, AB, and SB conducted the clinical trials used in the analysis.
References [1] Bhutani S, Klempel MC, Kroeger CM, Trepanowski JF, Varady KA. Alternate day fasting and endurance exercise combine to reduce body weight and favorably alter plasma lipids in obese humans. Obesity 2013;21:1370—9. [2] Eshghinia S, Mohammadzadeh F. The effects of modified alternate-day fasting diet on weight loss and CAD risk factors in overweight and obese women. J Diab Metab Disord 2013;12:4.
5 [3] Hoddy KK, Kroeger CM, Trepanowski JF, Barnosky A, Bhutani S, Varady KA. Meal timing during alternate day fasting: impact on body weight and cardiovascular disease risk in obese adults. Obesity 2014;22:2524—31. [4] Johnson JB, Summer W, Cutler RG, Martin B, Hyun DH, Dixit VD, et al. Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma. Free Rad Biol Med 2007;42:665—74. [5] Klempel MC, Kroeger CM, Varady KA. Alternate day fasting (ADF) with a high-fat diet produces similar weight loss and cardio-protection as ADF with a low-fat diet. Metab: Clin Exp 2013;62:137—43. [6] Varady KA, Bhutani S, Church EC, Klempel MC. Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and cardioprotection in obese adults. Am J Clin Nutr 2009;90:1138—43. [7] Halberg N, Henriksen M, Soderhamn N, Stallknecht B, Ploug T, Schjerling P, et al. Effect of intermittent fasting and refeeding on insulin action in healthy men. J Appl Physiol 2005;99:2128—36. [8] Heilbronn LK, Smith SR, Martin CK, Anton SD, Ravussin E. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. Am J Clin Nutr 2005;81:69—73. [9] Delahanty LM, Peyrot M, Shrader PJ, Williamson DA, Meigs JB, Nathan DM, et al. Pretreatment, psychological, and behavioral predictors of weight outcomes among lifestyle intervention participants in the Diabetes Prevention Program (DPP). Diab Care 2013;36:34—40. [10] Hadziabdic MO, Mucalo I, Hrabac P, Matic T, Rahelic D, Bozikov V. Factors predictive of drop-out and weight loss success in weight management of obese patients. J Human Nutr Diet: Off J Br Diet Assoc 2015;28(Suppl. 2):24—32. [11] Jackson SE, Beeken RJ, Wardle J. Predictors of weight loss in obese older adults: findings from the USA and the UK. Obes Facts 2014;7:102—10. [12] Stajkovic S, Aitken EM, Holroyd-Leduc J. Unintentional weight loss in older adults. CMAJ: Can Med Assoc J = journal de l’Association medicale canadienne 2011;183:443—9. [13] LaRose JG, Leahey TM, Hill JO, Wing RR. Differences in motivations and weight loss behaviors in young adults and older adults in the National Weight Control Registry. Obesity 2013;21:449—53. [14] Davis EM, Clark JM, Carrese JA, Gary TL, Cooper LA. Racial and socioeconomic differences in the weight-loss experiences of obese women. Am J Publ Health 2005;95: 1539—43. [15] Karlsen TI, Sohagen M, Hjelmesaeth J. Predictors of weight loss after an intensive lifestyle intervention program in obese patients: a 1-year prospective cohort study. Health Qual Life Outcomes 2013;11:165. [16] Ard JD, Rosati R, Oddone EZ. Culturally-sensitive weight loss program produces significant reduction in weight, blood pressure, and cholesterol in eight weeks. J Natl Med Assoc 2000;92:515—23. [17] Bishop J, Irby MB, Isom S, Blackwell CS, Vitolins MZ, Skelton JA. Diabetes prevention, weight loss, and social support: program participants’ perceived influence on the health behaviors of their social support system. Fam Community Health 2013;36:158—71.
Available online at www.sciencedirect.com
ScienceDirect Please cite this article in press as: Varady KA, et al. Determinants of weight loss success with alternate day fasting. Obes Res Clin Pract (2015), http://dx.doi.org/10.1016/j.orcp.2015.08.020
ARTICLE IN PRESS
Obesity Research & Clinical Practice (2015) xxx, xxx—xxx
SHORT REPORT
Determinants of weight loss success with alternate day fasting Krista A. Varady ∗, Kristin K. Hoddy, Cynthia M. Kroeger, John F. Trepanowski, Monica C. Klempel, Adrienne Barnosky, Surabhi Bhutani Department of Kinesiology and Nutrition, University of Illinois at Chicago, 1919 West Taylor Street, Chicago, IL, USA Received 15 July 2015 ; received in revised form 24 August 2015; accepted 30 August 2015
KEYWORDS Weight loss success; Determinants; Demographics; Body weight; Obese adults
Summary This study examined what characteristics predict weight loss success with alternate day fasting (ADF). Four 8-week trials of ADF (n = 121) were included in the analysis. Subjects aged 50—59 y achieved greater (P = 0.01) weight loss than other age groups. Males and females achieved similar weight loss. Caucasian subjects achieved greater (P = 0.03) weight loss than other races. Baseline body weight and baseline BMI did not predict degree of weight loss achieved with the diet. These findings may help clinicians to decide which population groups may benefit most from an ADF approach. © 2015 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
Introduction Alternate day fasting (ADF) is effective for weight loss. ADF involves a ‘‘fast day’’ where an individual consumes 25% of their energy needs as a lunch or dinner, alternated with a ‘‘feast day’’ where a person is permitted to eat ad libitum (with no ∗
Corresponding author at: Department of Kinesiology and Nutrition, University of Illinois at Chicago, 1919 West Taylor Street, Room 506F, Chicago, IL 60612, USA. Tel.: +1 312 996 7897; fax: +1 312 413 0319. E-mail address: [email protected] (K.A. Varady).
limitations on type or quantity of food consumed). Other forms of alternate day fasting, which involve a complete fast on the fast day (i.e. consuming water only), have also been examined. Eight shortterm ADF trials have been performed to date [1—8]. Results from these studies report body weight decreases of 3—8% after 2—12 weeks of treatment [1—8]. However, in these studies, the distribution of weight loss success varied widely. For instance, in pooling the data, we observed that ∼5% of individuals gained weight with ADF, ∼5% lost no weight, ∼25% lost <4% of weight, ∼60% lost 4—8% of weight, and ∼5% lost >8% of baseline body weight [1,3,5,6].
http://dx.doi.org/10.1016/j.orcp.2015.08.020 1871-403X/© 2015 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Varady KA, et al. Determinants of weight loss success with alternate day fasting. Obes Res Clin Pract (2015), http://dx.doi.org/10.1016/j.orcp.2015.08.020
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The reason why certain individuals respond better than others to ADF, remains unclear. Accordingly, this pilot study was undertaken to examine if certain key characteristics, namely age, sex, race/ethnicity or baseline body weight/BMI, can predict weight loss success with ADF.
Methods Study selection The data used in this analysis are from four separate 8-week trials of ADF performed by our lab group. Full details regarding subject selection, interventions, and outcome measures have been published elsewhere [1,3,5,6]. These four studies [1,3,5,6] were selected because they had similar population groups, and comparable ADF interventions in terms of study diet and trial duration. It should also be noted that, when a study employed multiple intervention arms, only the ADF diet arm (low fat or high fat background diet) was used in the analysis. For the study [1] that combined ADF plus exercise, only the ADF diet arm was used in the present analysis. Moreover, if the study duration exceeded 8 weeks, the 8-week data points were used as the final time points.
Study populations and diets Subject selection procedures were almost identical between the four studies [1,3,5,6]. In brief, subjects were recruited from the Chicago area by advertisements. Key inclusion criteria were as follows: male or female, age 25—65 y, BMI between 30 and 45 kg/m2 , weight stable, previously sedentary or lightly active, non-diabetic, non-smoker, and no history of cardiovascular disease. Experimental protocols were approved by the Office for the Protection of Research Subjects at the University of Illinois, Chicago, and all volunteers gave written informed consent. All subjects participated in an 8-week ADF protocol. During the ADF diet, subjects consumed 25% of their baseline energy needs on the fast day (24 h), and ate ad libitum on each alternating feast day (24 h).
Measures Demographic information, including age, sex, race, and ethnicity, was collected at baseline. For the present analysis, age was subcategorised as 25—29 y, 30—39 y, 40—49 y, 50—59 y, or 60—65 y. Race/ethnicity was categorised as African American, Caucasian, or Hispanic, and sex was
categorised as male or female. A total of n = 2 Asian subjects were recruited across all studies. Because this number of Asian subjects is so low, these subjects were removed from the analysis of race/ethnicity (Fig. 2A and B). There were no selfreported mixed-race or mixed-ethnicity individuals in any of the studies. Two individuals had participated in more than one study. The data for these subjects was used only once, and was removed from data sets of subsequent studies. Body weight was measured using a balance beam scale (HealthOMeter, Boca Raton, FL) at the research centre at baseline and week 8. Baseline body weight was categorised as 70—84.9 kg, 85—99.9 kg, 100—114.5 kg, or 115—129.9 kg. Baseline body mass index (BMI) was calculated as kg/m2 , and was subcategorised as 25—29.9 kg/m2 , 30—34.9 kg/m2 , 35—39.9 kg/m2 , and 40—44.9 kg/m2 . Weight loss was calculated as the absolute change in body weight between week 8 and week 0 (baseline).
Statistics Results are presented as mean ± SEM. Shapiro—Wilk tests for normality were included in the model. No variables were found to be not normal. Homogeneity of variance was tested by Levene’s test, and the variances were not statistically different from each other. A one-way ANOVA was used to test whether degree of weight loss differed between subcategories for each variable. When a significant difference was found between groups (P < 0.05), a Tukey post hoc test was performed to determine the differences between group means. Differences were considered significant at P < 0.05. All data was analysed using SPSS software (version 21.0, SPSS Inc, Chicago, IL).
Results A total of 121 subjects were included in the analysis. The degree of weight loss achieved by subjects of varying age ranges is portrayed in Fig. 1A and B. Results reveal that subjects aged 50—59.9 y achieved greater (P = 0.01) absolute and percent weight loss than subjects in other age groups. As for sex differences, there were no differences in the degree of weight loss achieved by male versus female subjects (Fig. 1C and D). Amount of weight loss achieved by subjects of varying races is displayed in Fig. 2A and B. Caucasian subjects achieved greater absolute (P = 0.03) and percent (P = 0.04) weight loss than African American and Hispanic subjects. When subjects were subcategorised by baseline body weight, there
Please cite this article in press as: Varady KA, et al. Determinants of weight loss success with alternate day fasting. Obes Res Clin Pract (2015), http://dx.doi.org/10.1016/j.orcp.2015.08.020
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Figure 1 Degree of weight loss by age group and sex. Values reported as mean ± SEM. Means not sharing a common superscript letter are significantly different at P < 0.05 based on a Tukey post hoc test. (A) Subjects aged 50—59.9 years achieved greater (P = 0.01) absolute weight loss than subjects in other age groups. (B) Subjects aged 50—59.9 years achieved greater (P = 0.01) percent weight loss than subjects in other age groups. Number of subjects: 25—29 y (n = 10), 30—39 y (n = 36), 40—49 y (n = 34), 50—59 y (n = 34), 60—65 y (n = 7). (C) No difference between females and males for absolute weight loss achieved. (D) No difference between females and males for percent weight loss achieved. Number of subjects: female (n = 107), male (n = 14).
were no differences between subcategories for absolute weight loss (Fig. 2C) or percent weight loss (Fig. 2D). Moreover, when subjects were subcategorised by baseline BMI, there were no differences between subcategories for absolute weight loss (Fig. 2E) or percent weight loss (Fig. 2F).
Discussion This is the first study to examine whether certain characteristics, namely age, sex, race/ethnicity, or baseline body weight predict weight loss success with ADF. We show here that older individuals (50—59 y) and Caucasian subjects may lose greater amounts of weight with ADF when compared to other age groups or races. Sex, baseline body weight, and baseline BMI had no impact on the degree of weight loss achieved with this diet. Our findings are in accordance with other trials showing that older individuals have more success
with dietary restriction [9—11]. Although the reason for this remains unclear, it is possible that the biology of older adults [12], and the cultural norms (i.e. being able to follow prescribed instructions more so than younger adults), predisposes them to greater weight loss [13]. It is also unclear why Caucasian subjects lost more weight with this protocol. It should be noted, however, that socioeconomic status was not measured in this study, and may confound the relationship between race and weight loss success [14,15]. Another confounding variable may be the types of foods (i.e. pizza, pasta, chicken dishes, etc.) provided to subjects during the dietary intervention periods of the studies. These diets were flawed in that they were not culturally sensitive [16], and as such, may have not been very palatable to individuals of varying cultural backgrounds. This lower palatability may have resulted in blunted adherence and weight loss. Interestingly, sex, baseline body weight, and baseline BMI had no impact on weight loss success.
Please cite this article in press as: Varady KA, et al. Determinants of weight loss success with alternate day fasting. Obes Res Clin Pract (2015), http://dx.doi.org/10.1016/j.orcp.2015.08.020
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Figure 2 Degree of weight loss by race/ethnicity, baseline body weight, and baseline BMI. Values reported as mean ± SEM. Means not sharing a common superscript letter are significantly different at P < 0.05 based on a Tukey post hoc test. (A) Caucasian subjects achieved greater (P = 0.03) absolute weight loss than African American and Hispanic subjects. (B) Caucasian subjects achieved greater (P = 0.04) percent weight loss than African American and Hispanic subjects. Number of subjects: African American (n = 65), Caucasian (n = 23), Hispanic (n = 31). (C) No difference for absolute weight loss when subjects were subcategorised by baseline body weight. (D) No difference for percent weight loss when subjects were subcategorised by baseline body weight. Number of subjects: 70—84 kg (n = 37), 85—99 kg (n = 49), 100—114 kg (n = 30), 115—129 kg (n = 5). (E) No difference for absolute weight loss when subjects were subcategorised by baseline BMI. (F) No difference for percent weight loss when subjects were subcategorised by baseline BMI. Number of subjects: 25—29.9 kg/m2 (n = 8), 30—34.9 kg/m2 (n = 62), 35—39.9 kg/m2 (n = 45), 40—44.9 kg/m2 (n = 6).
However, since our sample was quite small (n = 121), we may have lacked the power to detect differences between subcategories of these variables. This pilot study has several limitations. First, we did not measure other key determinants of weight loss success, namely education level, marriage status, number of children, employment status, and income level. Each of these variables play important roles in an individual’s weight loss journey, and may act as confounders in the present analysis. Second, we did not perform multivariable logistic regression to assess the independent contributions of age, sex, race/ethnicity and body weight in
predicting weight loss. Third, we did not assess how social support may have affected our findings [17]. Future trials in this area should implement a comprehensive demographics questionnaire, social support scale, and regression analysis to answer these important questions. Fourth, we did not examine how subject compliance related to weight loss success. Although we measured compliance in some of our studies via food records [1,5,6], we observed that the subjects who lost little or no weight were also the subjects who did not return their records. Thus, the compliance data for these subjects is unknown. This also makes it difficult to
Please cite this article in press as: Varady KA, et al. Determinants of weight loss success with alternate day fasting. Obes Res Clin Pract (2015), http://dx.doi.org/10.1016/j.orcp.2015.08.020
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Determinants of weight loss with alternate day fasting correlate compliance with weight loss success since most of the compliance data is missing for the subjects on the lower end of the weight loss scale. For this reason, we did not include the compliance data in the present analysis. Fifth, some of the subcategories had a relatively small n in comparison to the others. This is particularly true for the ‘‘male’’ sex subcategory, ‘‘60—65 y’’ age subcategory, ‘‘115—129 kg’’ baseline body weight subcategory, and the ‘‘40—44.9 kg/m2 ’’ baseline BMI subcategory. The small number of participants in each of these subcategories may limit our power to detect differences between groups. This should be taken into consideration when interpreting these data. In summary, these preliminary findings may help clinicians to decide which population groups may benefit most from an ADF approach. These data, however, warrant confirmation in a large-scale clinical trial that addresses each of the abovementioned limitations.
Funding source Departmental funding, Kinesiology and Nutrition, University of Illinois at Chicago.
Conflict of interest Krista Varady is the author of the book ‘‘The Every Other Day Diet’’ published by the Hachette Book Group. The other authors have no competing interests to disclose.
Acknowledgements KAV designed the experiment, analysed the data, and wrote the manuscript. KKH, CMK, JFT, MCK, AB, and SB conducted the clinical trials used in the analysis.
References [1] Bhutani S, Klempel MC, Kroeger CM, Trepanowski JF, Varady KA. Alternate day fasting and endurance exercise combine to reduce body weight and favorably alter plasma lipids in obese humans. Obesity 2013;21:1370—9. [2] Eshghinia S, Mohammadzadeh F. The effects of modified alternate-day fasting diet on weight loss and CAD risk factors in overweight and obese women. J Diab Metab Disord 2013;12:4.
5 [3] Hoddy KK, Kroeger CM, Trepanowski JF, Barnosky A, Bhutani S, Varady KA. Meal timing during alternate day fasting: impact on body weight and cardiovascular disease risk in obese adults. Obesity 2014;22:2524—31. [4] Johnson JB, Summer W, Cutler RG, Martin B, Hyun DH, Dixit VD, et al. Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma. Free Rad Biol Med 2007;42:665—74. [5] Klempel MC, Kroeger CM, Varady KA. Alternate day fasting (ADF) with a high-fat diet produces similar weight loss and cardio-protection as ADF with a low-fat diet. Metab: Clin Exp 2013;62:137—43. [6] Varady KA, Bhutani S, Church EC, Klempel MC. Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and cardioprotection in obese adults. Am J Clin Nutr 2009;90:1138—43. [7] Halberg N, Henriksen M, Soderhamn N, Stallknecht B, Ploug T, Schjerling P, et al. Effect of intermittent fasting and refeeding on insulin action in healthy men. J Appl Physiol 2005;99:2128—36. [8] Heilbronn LK, Smith SR, Martin CK, Anton SD, Ravussin E. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. Am J Clin Nutr 2005;81:69—73. [9] Delahanty LM, Peyrot M, Shrader PJ, Williamson DA, Meigs JB, Nathan DM, et al. Pretreatment, psychological, and behavioral predictors of weight outcomes among lifestyle intervention participants in the Diabetes Prevention Program (DPP). Diab Care 2013;36:34—40. [10] Hadziabdic MO, Mucalo I, Hrabac P, Matic T, Rahelic D, Bozikov V. Factors predictive of drop-out and weight loss success in weight management of obese patients. J Human Nutr Diet: Off J Br Diet Assoc 2015;28(Suppl. 2):24—32. [11] Jackson SE, Beeken RJ, Wardle J. Predictors of weight loss in obese older adults: findings from the USA and the UK. Obes Facts 2014;7:102—10. [12] Stajkovic S, Aitken EM, Holroyd-Leduc J. Unintentional weight loss in older adults. CMAJ: Can Med Assoc J = journal de l’Association medicale canadienne 2011;183:443—9. [13] LaRose JG, Leahey TM, Hill JO, Wing RR. Differences in motivations and weight loss behaviors in young adults and older adults in the National Weight Control Registry. Obesity 2013;21:449—53. [14] Davis EM, Clark JM, Carrese JA, Gary TL, Cooper LA. Racial and socioeconomic differences in the weight-loss experiences of obese women. Am J Publ Health 2005;95: 1539—43. [15] Karlsen TI, Sohagen M, Hjelmesaeth J. Predictors of weight loss after an intensive lifestyle intervention program in obese patients: a 1-year prospective cohort study. Health Qual Life Outcomes 2013;11:165. [16] Ard JD, Rosati R, Oddone EZ. Culturally-sensitive weight loss program produces significant reduction in weight, blood pressure, and cholesterol in eight weeks. J Natl Med Assoc 2000;92:515—23. [17] Bishop J, Irby MB, Isom S, Blackwell CS, Vitolins MZ, Skelton JA. Diabetes prevention, weight loss, and social support: program participants’ perceived influence on the health behaviors of their social support system. Fam Community Health 2013;36:158—71.
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ScienceDirect Please cite this article in press as: Varady KA, et al. Determinants of weight loss success with alternate day fasting. Obes Res Clin Pract (2015), http://dx.doi.org/10.1016/j.orcp.2015.08.020