Effects of isoenergetic overfeeding of either carbohydrate or fat in young men

Abstract

Ten pairs of normal men were overfed by 5 MJ/d for 21 d with either a carbohydrate-rich or a fat-rich diet (C- and F-group). The two subjects in each pair were requested to follow each other throughout the day to ensure similar physical activity and were otherwise allowed to maintain normal daily life. The increase in body weight, fat free mass and fat mass showed great variation, the mean increases being 1·5 kg, 0·6 kg and 0·9 kg respectively. No significant differences between the C- and F-group were observed. Heat production during sleep did not change during overfeeding. The RQ during sleep was 0·86 and 0·78 in the C- and F-group respectively. The accumulated faecal loss of energy, DM, carbohydrate and protein was significantly higher in the C- compared with the F-group (30, 44, 69 and 51 % higher respectively), whereas the fat loss was the same in the two groups. N balance was not different between the C- and F-group and was positive. Fractional contribution from hepatic de novo lipogenesis, as measured by mass isotopomer distribution analysis after administration of [1-13C]acetate, was 0·20 and 0·03 in the C-group and the F-group respectively. Absolute hepatic de novo lipogenesis in the C-group was on average 211 g per 21 d. Whole-body de novo lipogenesis, as obtained by the difference between fat mass increase and dietary fat available for storage, was positive in six of the ten subjects in the C-group (mean 332 (SEM 191) g per 21 d). The change in plasma leptin concentration was positively correlated with the change in fat mass. Thus, fat storage during overfeeding of isoenergetic amounts of diets rich in carbohydrate or in fat was not significantly different, and carbohydrates seemed to be converted to fat by both hepatic and extrahepatic lipogenesis.

Effect of Dietary Protein Content on Weight Gain, Energy Expenditure, and Body Composition During Overeating

“…Harris et al 32 also noted that resting energy expenditure increased early during overfeeding, suggesting that it is responding to the increased thermic effect of feeding more than the increase in body mass. The extra calories in our study were fed as fat, as in several other studies, 33,34 and were stored as fat with a lower percentage of the excess calories appearing as fat in the high (25%) protein diet group. The higher fat intake in the low protein group probably reduced nutrient absorption (metabolizable energy) relative to the other groups and this would have brought the intake and expenditure closer together in this group.…”

Nutrition and human health from a sex–gender perspective

“…In fact, the decrease in fat calories has resulted in an increase in carbohydrate calories, primarily in the form of simple sugars (Willett, 1998), and high-carbohydrate low-fat diets can produce high triglycerides and LDL levels and elevate weight gain (Lammert et al, 2000). Hypertriglyceridemia is of special importance in women as a cardiovascular risk factor (Collins et al, 2009;Mosca et al, 2007), and the triglyceride levels in women continue to increase with age.…”

Deficits in gastrointestinal responses controlling food intake and body weight

“…For example, plasma GLP-1 levels are reduced in obesity (224), which is reversed by weight loss (222). Dietary fat intake that is equicaloric to high-carbohydrate diets has been associated with body fat and weight status in children (107,108,136). Comparatively, rats with DIO eat more fat equicaloric to carbohydrate (93,227); however, hyperphagia is not always necessary for weight gain under HF conditions (163,164).…”