Randomized controlled trial of changes in dietary carbohydrate/fat ratio and simple vs complex carbohydrates on body weight and blood lipids: the CARMEN study

Abstract

OBJECTIVE: To investigate the long-term effects of changes in dietary carbohydrateafat ratio and simple vs complex carbohydrates. DESIGN: Randomized controlled multicentre trial (CARMEN), in which subjects were allocated for 6 months either to a seasonal control group (no intervention) or to one of three experimental groups: a control diet group (dietary intervention typical of the average national intake); a low-fat high simple carbohydrate group; or a low-fat high complex carbohydrate group. SUBJECTS: Three hundred and ninety eight moderately obese adults. MEASUREMENTS: The change in body weight was the primary outcome; changes in body composition and blood lipids were secondary outcomes. RESULTS: Body weight loss in the low-fat high simple carbohydrate and low-fat high complex carbohydrate groups was 0.9 kg (P`0.05) and 1.8 kg (P`0.001), while the control diet and seasonal control groups gained weight (0.8 and 0.1 kg, NS). Fat mass changed by 7 1.3 kg (P`0.01), 7 1.8 kg (P`0.001) and 0.6 kg (NS) in the low-fat high simple carbohydrate, low-fat high complex carbohydrate and control diet groups, respectively. Changes in blood lipids did not differ signi®cantly between the dietary treatment groups. CONCLUSION: Our ®ndings suggest that reduction of fat intake results in a modest but signi®cant reduction in body weight and body fatness. The concomitant increase in either simple or complex carbohydrates did not indicate signi®cant differences in weight change. No adverse effects on blood lipids were observed. These ®ndings underline the importance of this dietary change and its potential impact on the public health implications of obesity.

Randomized, multi-center trial of two hypo-energetic diets in obese subjects: high- versus low-fat content

“…7 Our results suggest that a larger proportion of obese subjects achieve a major weight loss, that is, more than 10%, and fewer will drop out on the low-fat diet. This is in line with previous ad libitum studies, [4][5][6] and suggests that energy from carbohydrate are slightly more satiating than those from fat also under conditions with a fixed energy deficit.…”

“…The intervention package included prescribed energy intake based upon an individually measured resting metabolic rate in contrast to others who used a fixed energy intake target. 7,8 A tailored dietary program was used, in contrast to one other study, which used a limited menu cycle, 6 and a high level of support was offered to the subjects.…”

“…8 Other studies with smaller subject numbers showed either a limited 7 or no effect. 6 The decrease in the blood lipids is primarily a result of the weight loss per se. The present study additionally demonstrates that both diets have beneficial effects on blood lipids.…”

“…Meta-analyses of intervention trials have demonstrated that ad libitum low-fat diets produce 3-4 kg weight loss over 3-6 months, 4 and there is some evidence to suggest that weight maintenance is easier to achieve by a fat-reduced diet than with a higher fat diet. 5 While there is little evidence to support any important difference between low-fat diets with complex and simple carbohydrates, 6 higher protein levels might improve weight loss. 7 However, very few randomized trials have been conducted, which combine energy restriction and compare different levels of energy from fat and carbohydrate.…”

Dietary glycaemic index, glycaemic load and subsequent changes of weight and waist circumference in European men and women

“…Both low-fat highcarbohydrate diets and low-carbohydrate high-fat diets have been found to be effective strategies for weight loss in intervention studies. [43][44][45][46] In our study, when carbohydrate intake was analysed in the same regression models as used for GL, no association with weight and waist circumference change was observed. Also noteworthy, the correlation coefficient between GL and carbohydrates was 0.98, whereas it was only 0.36 between GL and GI (data not shown).…”