Ghrelin and measures of satiety are altered in polycystic ovary syndrome but not differentially affected by diet composition

Polycystic ovary syndrome (PCOS) is a common endocrine condition in women of reproductive age associated with obesity. It may involve dysregulation of ghrelin, a hormone implicated in appetite regulation. The effect of diet composition on ghrelin is unclear. Overweight women with and without PCOS were randomized to a high-protein (40% carbohydrate, 30% protein; 10 PCOS, six non-PCOS) or standard protein diet (55% carbohydrate, 15% protein; 10 PCOS, six non-PCOS) for 12 wk of energy restriction and 4 wk of weight maintenance. Diet composition had no effect on fasting or postprandial ghrelin or measures of satiety. Non-PCOS subjects had a 70% higher fasting baseline ghrelin (P = 0.011), greater increase in fasting ghrelin (57.5 vs. 34.0%, P = 0.033), and greater maximal decrease in postprandial ghrelin after weight loss (-144.1 +/- 58.4 vs. -28.9 +/- 14.2 pg/ml, P = 0.02) than subjects with PCOS. Subjects with PCOS were less satiated (P = 0.001) and more hungry (P = 0.007) after a test meal at wk 0 and 16 than subjects without PCOS. Appetite regulation, as measured by subjective short-term hunger and satiety and ghrelin homeostasis, may be impaired in PCOS.

Long-term effects of a high-protein, low-carbohydrate diet on weight control and cardiovascular risk markers in obese hyperinsulinemic subjects

OBJECTIVE

To compare the long-term compliance and effects of two low-fat diets differing in carbohydrate to protein ratio on body composition and biomarkers of cardiovascular disease risk in obese subjects with hyperinsulinemia.

DESIGN

Outpatient, parallel, clinical intervention study of two groups of subjects randomly assigned to either a standard protein (SP; 15% protein, 55% carbohydrate) or high-protein (HP; 30% protein, 40% carbohydrate) diet, during 12 weeks of energy restriction (approximately 6.5 MJ/day) and 4 weeks of energy balance (approximately 8.3 MJ/day). Subsequently, subjects were asked to maintain the same dietary pattern for the succeeding 52 weeks with minimal professional support.

SUBJECTS

A total of 58 obese, nondietetic subjects with hyperinsulinemia (13 males/45 females, mean age 50.2 y, mean body mass index (BMI) 34.0 kg/m2, mean fasting insulin 17.8 mU/l) participated in the study.

MEASUREMENTS

: Body composition, blood pressure, blood lipids, fasting glucose, insulin, CRP and sICAM-1 were measured at baseline and at weeks 16 and 68. Urinary urea/creatinine ratio was measured at baseline, week 16 and at 3 monthly intervals thereafter.

RESULTS

In total, 43 subjects completed the study with similar dropouts in each group (P=0.76). At week 68, there was net weight loss (SP -2.9+/-3.6%, HP -4.1+/-5.8%; P<0.44) due entirely to fat loss (P<0.001) with no diet effect [corrected]. Both diets significantly increased HDL cholesterol concentrations (P<0.001) and decreased fasting insulin, insulin resistance, sICAM-1 and CRP levels (P<0.05). Protein intake was significantly greater in HP during the initial 16 weeks (P<0.001), but decreased in HP and increased in SP during 52-week follow-up, with no difference between groups at week 68, indicating poor long-term dietary adherence behaviour to both dietary patterns.

CONCLUSION

Without active ongoing dietary advice, adherence to dietary intervention is poor. Nonetheless, both dietary patterns achieved net weight loss and improvements in cardiovascular risk factors.

Effect of a high-protein, energy-restricted diet on weight loss and energy expenditure after weight stabilization in hyperinsulinemic subjects

OBJECTIVE

To determine the effect of replacing some dietary carbohydrate with protein, during energy restriction, on weight loss, total energy expenditure (TEE), resting energy expenditure (REE), respiratory quotient (RQ), and the thermic effect of feeding (TEF) in subjects with hyperinsulinemia.

DESIGN

Parallel, clinical intervention study of 12 weeks energy restriction (6.5 MJ/day) and 4 weeks energy balance (8.2 MJ/day) in two groups of subjects randomly assigned to either a high-protein (HP) diet (27% of energy (%E) as protein, 45%E as carbohydrate) or a lower-protein (LP) diet (16%E as protein, 57%E as carbohydrate).

SUBJECTS

A total of 36 obese nondiabetic volunteers with hyperinsulinemia (10 males/26 females, aged 34-65 y, BMI 28-43 kg/m(2), fasting insulin 12-45 mU/l).

MEASUREMENTS

Body weight and composition, TEE, REE, and RQ were measured at baseline and at week 16. In addition, the TEF to an HP or LP meal was determined for 3 h, at baseline and at week 16.

RESULTS

After 16 weeks, weight loss was similar in response to each diet; the overall decrease was 7.9+/-0.6 kg (P<0.001), of which 6.8+/-0.5 kg was fat (P<0.001). REE fell similarly with each diet; the overall decrease was 719+/-106 kJ/day (P<0.001). The TEF was 2% greater after the HP than after the LP meal at baseline (P<0.01) and 0.8% greater at week 16 (P=0.35). After 16 weeks, the TEF was not reduced in either dietary group. There was no change in TEE after 16 weeks.

CONCLUSION

In subjects with hyperinsulinemia an energy-restrictive diet containing an increased protein-to-carbohydrate ratio does not enhance weight loss or significantly affect energy expenditure. Caloric restriction, rather than the macronutrient composition of the diet, is the most important determinant of weight loss.

Effects of energy-restricted diets containing increased protein on weight loss, resting energy expenditure, and the thermic effect of feeding in type 2 diabetes

OBJECTIVE

To determine the effect of a high-protein (HP) diet compared with a low-protein (LP) diet on weight loss, resting energy expenditure (REE), and the thermic effect of food (TEF) in subjects with type 2 diabetes during moderate energy restriction.

RESEARCH DESIGN AND METHODS

In this study, 26 obese subjects with type 2 diabetes consumed a HP (28% protein, 42% carbohydrate) or LP diet (16% protein, 55% carbohydrate) during 8 weeks of energy restriction (1,600 kcal/day) and 4 weeks of energy balance. Body weight and composition and REE were measured, and the TEF in response to a HP or LP meal was determined for 2 h, at weeks 0 and 12.

RESULTS

The mean weight loss was 4.6 +/- 0.4 kg (P < 0.001), of which 4.5 +/- 0.4 kg was fat (P < 0.001), with no effect of diet (P = 0.6). At both weeks 0 and 12, TEF was greater after the HP than after the LP meal (0.064 vs. 0.050 kcal x kcal(-1) energy consumed x 2 h(-1), respectively; overall diet effect, P = 0.003). REE and TEF were reduced similarly with each of the diets (time effects, P = 0.02 and P < 0.001, respectively).

CONCLUSIONS

In patients with type 2 diabetes, a low-fat diet with an increased protein-to-carbohydrate ratio does not significantly increase weight loss or blunt the fall in REE.

Diets high and low in glycemic index versus high monounsaturated fat diets: effects on glucose and lipid metabolism in NIDDM

OBJECTIVE

To examine the relative effects of high and low glycemic index (GI) carbohydrates, and monounsaturated fats on blood glucose and lipid metabolism in NIDDM subjects.

SUBJECTS

Fourteen male and seven female variably controlled NIDDM subjects recruited by advertisement.

SETTING

Free living outpatients.

RESEARCH DESIGN

A repeated measures, within-subject design was used such that each subject consumed three diets: (a) a high-GI diet (53% CHO -21% fat, 63 GI units (glucose= 100)); (b) a low-GI diet (51% CHO -23% fat, 43 GI units); and (c) a high-mono high-GI diet (42% CHO -35% fat, 59 GI units) in random order and cross-over fashion for four weeks. Approximately 45% energy was provided as key foods which differed in published GI values and specifically excluded legumes. Dietary fibre intake was > 30 g/d on each diet. At the end of each dietary intervention, we measured fasting plasma lipids, glucose, insulin, total glycated plasma protein, fructosamine, LDL and HDL particle size as well as 24 h urinary excretion of glucose and C-peptide.

RESULTS

HDL-cholesterol was higher on the low-GI and high-mono high-GI diets compared to the high-GI diet (P < 0.05 for overall diet effect). There were no other significant differences in metabolic control between diets, even when adjusted for BMI, glucose control or gender. Body weight and saturated fat intake remained stable between dietary interventions.

CONCLUSION

High-mono high-GI and high-CHO, low-GI diets are superior to high-CHO, high-GI diets with respect to HDL metabolism but no effect was noted on glucose metabolism in variably controlled NIDDM subjects.