Favourable metabolic effects of a eucaloric lower‐carbohydrate diet in women with PCOS

Abstract

Summary Objective Diet-induced reduction in circulating insulin may be an attractive nonpharmacological treatment for women with polycystic ovary syndrome (PCOS) among whom elevated insulin may exacerbate symptoms by stimulating testosterone synthesis. This study was designed to determine whether a modest reduction in dietary carbohydrate (CHO) content affects β-cell responsiveness, serum testosterone concentration and insulin sensitivity in women with PCOS. Design In a crossover design, two diets (‘Standard,’ STD, 55:18:27% energy from carbohydrate/protein/fat; lower-carbohydrate, 41:19:40) were provided for 8 weeks in random order with a 4-week washout between. Patients Thirty women with PCOS. Measurements β-cell responsiveness assessed as the C-peptide response to glucose during a liquid meal test; insulin sensitivity from insulin and glucose values throughout the test; insulin resistance (HOMA-IR); and total testosterone by immunoassay. Results Paired t-test indicated that the lower-CHO diet induced significant decreases in basal β-cell response (PhiB), fasting insulin, fasting glucose, HOMA-IR, total testosterone and all cholesterol measures, and significant increases in insulin sensitivity and dynamic (‘first-phase’) β-cell response. The STD diet induced a decrease in HDL-C and an increase in the total cholesterol- to-HDL-C ratio. Across all data combined, the change in testosterone was positively associated with the changes in fasting insulin, PhiB and insulin AUC (P < 0·05). Conclusions In women with PCOS, modest reduction in dietary CHO in the context of a weight-maintaining diet has numerous beneficial effects on the metabolic profile that may lead to a decrease in circulating testosterone.

Nutritional support and dietary interventions for women with polycystic ovary syndrome

“…85 One trial included a diet with <30% carbohydrates, six trials included diets with 40% carbohydrates and four studies with 41-45% carbohydrates. 41,42,76,83,[86][87][88][89][90][91][92] Douglas et al 92 compared the effects of three eucaloric diets: 1) standard (16% protein, 56% carbohydrate, 31% fat), 2) moderately low-carbohydrate (15% protein, 43% carbohydrate, 45% fat) and 3) high monounsaturated fatty acid (MUFA) diets (15% protein, 55% carbohydrate, 33% fat) on glucose and insulin responses in women with PCOS and reported greater reductions in fasting insulin (-3 mIU/L) and lower acute insulin response to glucose (-98 mIU/L × 10 minutes) with the moderately low-carbohydrate diet compared to other two diets. In contrast, results from two clinical trials reported no significant differences in glucose or energy metabolism with moderately low-carbohydrate diets.…”

“…76,78,[90][91][92]105,106,152 Moderately low-carbohydrate, high-fat diets have been shown to decrease fasting insulin and AUC for insulin and to increase insulin sensitivity in three trials in women with PCOS. [90][91][92] In one trial, a high-fat, moderately low-carbohydrate eucaloric diet resulted in greater reductions in body fat, intra-abdominal adipose tissue, subcutaneous abdominal adipose tissue and intermuscular adipose tissue compared to a control diet.…”

“…76,78,[90][91][92]105,106,152 Moderately low-carbohydrate, high-fat diets have been shown to decrease fasting insulin and AUC for insulin and to increase insulin sensitivity in three trials in women with PCOS. [90][91][92] In one trial, a high-fat, moderately low-carbohydrate eucaloric diet resulted in greater reductions in body fat, intra-abdominal adipose tissue, subcutaneous abdominal adipose tissue and intermuscular adipose tissue compared to a control diet. 76 Results from another trial comparing two isocaloric diets -a low-fat, low-saturated fat, high-carbohydrate (~15% protein, 60% carbohydrate, 25% fat, 7% saturated fat) or a high-fat, low-saturated fat, moderately low-carbohydrate diet (~15% protein, 40% carbohydrate, 45% fat, 7% saturated fat) -showed a 30% greater reduction in AUC for insulin and blood lipids with the high-fat, low-saturated fat, moderately low-carbohydrate diet, in the absence of weight loss.…”

“…92 Results from another crossover clinical trial showed that a high-fat and moderately low-carbohydrate (~41% carbohydrate, 19% protein and 40% fat) diet induced significant glucose metabolism improvements (decreased basal β-cell response, fasting insulin, fasting glucose and IR), hormonal responses (lower testosterone) and decreased blood lipids and adipose tissue (intra-abdominal adipose tissue [-7.1%], subcutaneous abdominal adipose tissue [-4.6%] and intermuscular adipose tissue [-11.5%]). 76,91 DASH diet is a low-GI, low-energy-density, high in complex carbohydrates, high fiber diet (~18% protein, 52% carbohydrate, 30% fat), which has been shown to produce significantly lower blood pressure and glycemic responses. 99,107 Asemi and Esmaillzadeh 78 demonstrated that adherence to DASH eating pattern, compared to a control diet based on Iranian traditional foods, resulted in greater reductions in body weight, BMI, WC, hip circumference (HC), serum insulin levels, IR, hsCRP and TG compared to the control diet in women with PCOS.…”

Substituting Poly and Mono-unsaturated Fat for Dietary CarbohydrateReduces Hyperinsulinemia in Women with Polycystic Ovary Syndrome

“…Two dietary weight loss studies that substituted protein for CHO showed no difference according to macronutrients [30,31], but the effect of weight loss or substitution of protein for CHO may have overridden any benefit from CHO restriction per se in lowering insulin concentrations. Two eucaloric studies with crossover design comparing moderate variations in dietary CHO (55% vs 40%), with mono/polyunsaturated fat substitution, showed significant reduction in fasting insulin after 3-8 weeks [32,33]. Day-long insulin response to replacement of dietary CHO with fat in the eucaloric state has not yet been reported in women with PCOS.…”