Journal Name:
Am. J. Clin. Nutr.
Article Title:
Comparison of 3 ad libitum diets for weight-loss maintenance, risk of cardiovascular disease, and diabetes: a 6-mo randomized, controlled trial.
Date Written:
2008
Volume:
88
Number:
5
Page:
1232
Author(s):
Due, A.; Larsen, T.M.; Mu, H.; Hermansen, K.; Stender, S.; Astrup, A.
Article:
The optimal dietary content and type of fat and carbohydrate for weight management has been debated for decades. Recent meta-analyses have found little evidence to support the consumption of a low-fat diet for weight reduction. Some studies indicate that the intake of unsaturated fat may not lead to the same weight gain as does an isocaloric diet high in saturated fatty acid (SFA). The challenge is not really to lose weight but to prevent weight gain and weight regain after weight loss. There is much contradictory data in this area and a lack of data from well-controlled trials about the most effective dietary approaches to maintaining a weight loss in overweight individuals.
The purpose of the present study was to compare the effect on weight-loss maintenance and change in cardiovascular disease and diabetic risk factors of 3 different ad libitum diets in a 6-mo controlled dietary maintenance intervention in healthy subjects. nondiabetic overweight or obese [mean +/- SD body mass index (in kg/m(2)): 31.5 +/- 2.6] men (n = 55) and women (n = 76) aged 28.2 +/- 4.8 y were randomly assigned to a diet providing a moderate amount of fat (35-45% of energy) and >20% of fat as monounsaturated fatty acids (MUFA diet; n = 54), to a low-fat (20-30% of energy) diet (LF diet; n = 51), or to a control diet (35% of energy as fat; n = 26). Protein constituted 10-20% of energy in all 3 diets.
More subjects dropped out of the MUFA (28%) group than out of the LF group (16%) and control group (8%) (MUFA compared with control: P < 0.05). All groups regained weight (MUFA: 2.5 +/- 0.7 kg; LF: 2.2 +/- 0.7 kg; and control: 3.8 +/- 0.8 kg; NS). Body fat regain was lower in the LF (0.6 +/- 0.6%) and MUFA (1.6 +/- 0.6%) groups than in the control group (2.6 +/- 0.5%). In the MUFA group, fasting insulin decreased by 2.6 +/- 3.5 pmol/L, the homeostasis model assessment of insulin resistance by 0.17 +/- 0.13, and the ratio of LDL to HDL by 0.33 +/- 0.13; in the LF group, these variables increased by 4.3 +/- 3.0 pmol/L and 0.17 +/- 0.10 and decreased by 0.02 +/- 0.09, respectively; and in the control group, increased by 14.0 +/- 4.3 pmol/L, 0.57 +/- 0.17, and 0.05 +/- 0.14, respectively. Dietary adherence was high on the basis of fatty acid changes in adipose tissue.
The present study showed that diet composition had no major effect on maintenance of weight loss during the 6-month controlled dietary intervention. However, the low-fat diet and the diet high in MUFA, caused a lower regain in body fat than did a typical Western diet. 50% of the 106 completers maintained a weight loss of >8%, but the finding that none of the tested diets were significantly superior in preventing weight regain suggests that the type of diet followed may not be particularly important for weight-loss maintenance. Even though energy density was higher in the MUFA diet, it was only in the control group that a 1 kJ/g increment in energy density was associated with a 4 kg regain of body fat. An increase in PUFA intake of 1% of energy predicted a lower regain of 2.7 kg body fat in only the MUFA group, which suggested that the type of fat could have an effect on body fat.
The MUFA diet caused a greater reduction in fasting insulin and an improvement in HOMA-IR. This favorable effect may have been caused by the higher intake of PUFA, because it was shown that an increase in PUFA intake of 1% of energy predicted an improvement of 0.5 mmol/L glucose, of 4 pmol/L insulin, and of 1 score in HOMA-IR. Although no difference in energy intake was found between groups in the present study, long-term studies are needed to see whether a greater intake of MUFAs and PUFAs results in a higher energy intake and thus may counteract the potential favorable effects on risk of diabetes and cardiovascular disease.
In conclusion, none of the tested diets were superior to one another in maintaining weight loss. The favorable effects of a low-fat diet (ie, lower body fat regain) and of high MUFA diets may not turn out to be very important if the weight is eventually regained. The real challenge is to maintain body weight loss and to prevent subsequent relapse.
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