Randomized Trial of a High Protein, Partial Meal Replacement Program with or without Alternate Day Fasting: Similar Effects on Weight Loss, Retention Status, Nutritional, Metabolic, and Behavioral Outcomes

Abstract

Higher-protein diets, meal replacements, and greater early weight loss have separately been associated with greater weight loss. We compared a high-protein, meal replacement program with daily energy restriction (DER) to one which provided greater energy restriction adding alternate day fasting (ADF + DER; alternating days of modified-fasting and DER plus 1 ad libitum day/week) on retention, weight loss, physiological, nutritional, and behavioral markers. Participants were randomized to ADF + DER or DER for 16 weeks (n = 162, age 40 ± 8 years BMI 36 ± 6 kg/m² (Mean ± SD)) plus 8 weeks weight maintenance. At week 16 weight change was -10.7 ± 0.5 kg and -11.2 ± 0.6 kg in ADF + DER and DER groups (treatment NS). Fat mass, visceral adipose tissue, and lean mass (p < 0.05) were similarly reduced between treatments. Weight loss was sustained to 24 weeks (treatment NS). Fasting LDL-cholesterol, triglycerides, insulin, hsCRP, glucose, and blood pressure all improved (p < 0.05; treatment NS). Transferrin saturation, ferritin, serum zinc, folate, and B12 improved (p < 0.05; treatment NS). Plasma thiamine and vitamin D levels decreased, reflecting lower carbohydrate intakes and seasonal changes, respectively. Food cravings, quality of life, and mood improved (treatment NS). Energy, fatigue, and pain improved slightly more in DER (p < 0.05). This study supports the use of higher protein, meal replacement programs with or without ADF in weight management.

Keywords: fasting; meal replacement; weight loss.

Figure 1

CONSORT diagram indicating sample size at each stage of the study. DER, standard meal replacement program; ADF + DER modified meal replacement program.

Figure 2

Mean ± standard error change in bodyweight after 16 weeks of the DER (n = 68) or ADF + DER diet (n = 67), followed by eight weeks of weight maintenance. DER, standard meal replacement program; ADF + DER modified meal replacement program. For between group differences, p > 0.05; for time effect p < 0.01; for group differences over time (time × diet interaction) p > 0.05, using linear mixed-effects model analysis.

Figure 3

Self-rated compliance (out of five stars) to dietary program for DER and ADF + DER groups. DER, standard meal replacement program; ADF + DER modified meal replacement program. For between-group differences, p > 0.05; for time effect, falls in compliance were significant between week 2 and all other visits (p < 0.05 to p < 0.001) for both groups; for group differences over time (time × diet interaction) p > 0.05, using linear mixed-effects model analysis.

Figure 4

Food Craving scores for those in the DER and ADF + DER groups. Note: scores based on Trait Food Craving Questionnaire: Total caving scores range min 21, max 126; Preoccupation with Food min 6, max 36; Loss of Control min 6, max 36; Emotional Craving min 4, max 24; Positive Outcome Expectancy min 5, max 30. DER, (n = 68) standard meal replacement program; ADF + DER (n = 67) modified meal replacement program; NS, not significant. For between-group differences, p > 0.05; for time effect falls in total cravings, loss of control, emotional cravings, and positive outcome expectancy, p < 0.0001; an interaction effect revealed a fall in preoccupation with food only for the DER group (p < 0.05), using linear mixed-effects model analysis.

Figure 5

Changes in health-related quality of life scores (MOS SF36) between baseline and week 16 presented by treatment. DER, (n = 68) standard meal replacement program; ADF + DER (n = 67) modified meal replacement program; Phys, Physical; Emo, Emotional; NS, not significant. Note: Scores out of a possible 100 with higher scores representing improved health-related quality of life. For between-group differences, p > 0.05; for time effect improvements in general health, physical functioning, energy, emotional wellbeing, pain p < 0.0001; an interaction effect revealed an improvement in role limitations due to physical function only for the DER group (p < 0.05), using linear mixed-effects model analysis.

Figure 6

Changes in mood (positive and negative affect) presented by dietary allocation. Note: Scores based on the Positive and Negative Affect Schedule with a range from 10 to 50 with higher scores representing higher levels of positive or negative emotions. DER, (n = 68) standard meal replacement program; ADF + DER (n = 67) modified meal replacement program. For between-group differences, p > 0.05; for time effect p < 0.01 for decrease in negative affect and p < 0.001 for increase in positive affect; the interaction effect was p > 0.05, using linear mixed-effects model analysis.