Comparison of the Effects on Insulin Sensitivity of High Carbohydrate and High Fat Diets in Normal Subjects*

Abstract

To examine whether achievable dietary changes influence insulin sensitivity, we performed euglycemic hyperinsulinemic glucose clamps in eight normal subjects who were prescribed high carbohydrate and high fat diets. The high carbohydrate diet was more than 50% (of energy intake) carbohydrate and less than 30% fat; the high fat diet was more than 45% fat (predominantly saturated) and less than 40% carbohydrate. The diets were consumed over consecutive 3-week periods in random sequence. The mean whole body glucose uptake during the glucose clamps was similar after the high carbohydrate (48.3 mumol/kg.min) and high fat diets (47.0 mumol/kg.min; P = 0.5; 95% confidence interval for the difference, -3.4 to 5.9 mumol/kg.min). Fasting blood glucose and serum insulin concentrations were also unchanged. In contrast, there were substantial effects on lipoprotein metabolism. During the high carbohydrate diet, fasting serum cholesterol decreased by 17% (P = 0.06), low density lipoprotein cholesterol decreased by 20% (P = 0.05), high density lipoprotein cholesterol decreased by 24% (P less than 0.005), and triglyceride increased by 33% (P = 0.06) compared with levels during the high fat diet. These results suggest that practically achievable high carbohydrate diets do not enhance insulin sensitivity in nondiabetic subjects and have net effects on lipoprotein metabolism that may be unfavorable.

Prolonged adaptation to fat-rich diet and training; effects on body fat stores and insulin resistance in man

“…This finding is consistent with the well-reported hypertriglyceridemic effects of carbohydrate rich diets. 22,23 The plasma ß-hydroxy-butyrate concentration was increased in the two groups that consumed the fat-rich diet, which is consistent with the reported ketogenic effect of fat-rich diets. 24 Furthermore the finding of a significantly higher muscle glycogen concentration after the consumption of the carbohydraterich diet and not in either of the groups that consumed the fat-rich diet is consistent with a higher carbohydrate intake.…”

Determinants of glycated haemoglobin in the general population: associations with diet, alcohol and cigarette smoking

“…After adjusting for these variables, there was no association between GHb and adult height (Ohlson et al, 1987), in contrast to some reports which associated type 2 diabetes with shorter stature (Brown et al, 1991). The inverse association between GHb and educational attainment was consistent with the well described inverse association between type 2 diabetes and socio-economic status (Rewers & Hamman, 1995).…”

“…Evidence that high-carbohydrate, high®bre diets contribute to improved insulin sensitivity in nondiabetic subjects is con¯icting (Fugakawa et al, 1990;Borkman et al, 1991) but Salmeron et al (1997) suggested that diets with a high glycaemic load and low cereal ®bre content contributed to the risk of type 2 diabetes. In an extensive review, Daly et al (1997) concluded that there was insuf®cient evidence from human studies to draw ®rm conclusions concerning the relation between dietary carbohydrate and insulin sensitivity.…”

The prevalence and risk factors for age-related macular degeneration in rural–urban India, Sankara Nethralaya Rural–Urban Age-related Macular degeneration study, Report No. 1

“…However, this evidence is not supported by prospective studies where dietary habits have been related to the development of NIDDM (188,189). The effects of a high carbohydrate diet on glucose tolerance have been equivocal (190,191). Hughes et al (192) compared the effects of a high carbohydrate (60% carbohydrate and 20% fat)/high fibre (25 g dietary fibre/1000 kcal th ) diet with, and without, three months of high-intensity endurance exercise (75% maximal heart rate reserve, 50 minutes/day, four days/week) in older glucoseintolerant men and women.…”