Long-term effects of popular dietary approaches on weight loss and features of insulin resistance

Abstract

Objective: High-carbohydrate (HC)-high-fibre diets are recommended for weight loss and for treating and preventing diseases such as diabetes and cardiovascular disease. We report a randomised trial comparing high-fat (HF) and high-protein (HP) diets with the conventional approach. Research design and methods: A total of 93 overweight insulin-resistant women received advice following randomisation to HF, HP or HC dietary regimes, to achieve weight loss followed by weight maintenance over 12 months. Weight, body composition and measures of carbohydrate and lipid metabolism were investigated. Results: Retention rates were 93% for HP and 75% for HC and HF. Features of the metabolic syndrome improved in all groups during the first 6 months, to a greater extent on HF and HP than an HC. During the second 6 months the HF group had increases in waist circumference (mean difference 4.4 cm (95% CI 3.0, 5.8)), fat mass (2.3 kg (1.5, 3.1)), triglycerides (0.28 mmol/l (0.09, 0.46)) and 2 h glucose (0.70 mmol/l (0.22, 1.18)). Overall there was substantial sustained improvement in waist circumference, triglycerides and insulin in the HP group and sustained but more modest changes on HC. Dietary compliance at 12 months was poor in all groups. Conclusions: HP and HC approaches appear to be appropriate options for insulin-resistant individuals. When recommending HP diets appropriate composition of dietary fat must be ensured. HC diet recommendations must include advice regarding appropriate high-fibre, low glycaemic index foods.

Carbohydrate intake and obesity

“…At 6 months, the higher protein diet was associated with a 5 energy percent higher protein intake (26 versus 21%) and a statistically significant 2.2 kg greater weight loss (6.9 versus 4.7 kg). Regain of weight in the subsequent 6 months was 0.5 kg for the high-carbohydrate and 0.9 kg for the highprotein group (McAuley et al, 2006). After 12 months, the energy percent of protein was identical for the two groups, whereas a non-statistically significant 2.3 kg lower body weight remained for the high-protein as compared with the high-carbohydrate group.…”

“…Table 2 shows the characteristics and results of five 12-month weight loss trials that randomized participants to very-low carbohydrate 'Atkins' type diets or low-fat diets (Foster et al, 2003;Samaha et al, 2003;Stern et al, 2004;Dansinger et al, 2005;McAuley et al, 2005McAuley et al, , 2006Gardner et al, 2007). In four of the five studies, a substantially larger weight loss was found after 6 months of the low-carbohydrate diet as compared with the low-fat diet (Foster et al, 2003;Samaha et al, 2003;McAuley et al, 2005;Gardner et al, 2007).…”

High-fibre, low-fat diet predicts long-term weight loss and decreased type 2 diabetes risk: the Finnish Diabetes Prevention Study

“…In recent studies [27][28][29] a low-carbohydrate diet resulted in more pronounced short-term weight reduction compared with a conventional low-energy, lowfat dietary regimen, probably because the achieved energy deficit was larger. However, the statistically significant difference in early weight loss between the groups disappeared at 12 months [27,30,31], indicating that individuals are not able to adhere to such a restricted diet. Moreover, the long-term safety of low-carbohydrate diets in weight-stable individuals is not known [32].…”

“…Moreover, the long-term safety of low-carbohydrate diets in weight-stable individuals is not known [32]. Still another popular, and evidently efficient [22,31] weight-loss approach is to increase protein intake up to 30% of total energy, with a decrease in either fat or carbohydrate. An increase in protein intake may increase patient satisfaction during a low-fat, energy-restricted diet [22] and has been shown to accelerate weight loss [33] and prevent weight regain [34].…”

Obesity Management in Women with Polycystic Ovary Syndrome

“…A smaller weight loss with HF diets could be due to the greater intake of energy-dense food in energycontrolled or ad libitum settings [90][91][92][93][94][95][96][97]. Some studies have shown that HF diets resulted in lower fasting and postprandial insulin compared with HC diets [90,[92][93][94]98,99].…”