HIGH PROTEIN, LOW-GI DIET AND BODY COMPOSITION

A high-protein, low-glycemic index (GI) diet combined with an exercise program can achieve significant changes in body composition and metabolic health after just 6 weeks, according to the findings of a new study.

The study included 44 men aged 30-40 years with abdominal obesity. They were randomly allocated to one of three groups:

• An exercise intervention group (16 men) who took part in an exercise program combining aerobic and resistance training three times per week for 1 hour, supervised by a personal trainer
• A combined diet and exercise intervention group (16 men) who took part in the same exercise program described above and followed an ad libitum (eating according to appetite) high-protein, low-GI diet
• A control group who did not undergo any intervention

The diet included low GI carbs such as fruits, vegetables and wholegrains and protein from low fat dairy, lean meat and fish. The goal was to have approximately 25% of energy from protein and fat and 50% from carbohydrate. Participants had regular dietary consultations and received individualised dietary recommendations, shopping lists, and recipes. They recorded their food intake in a phone app and were given feedback from a dietitian to ensure they were following the study’s dietary recommendations.

The researchers took measurements before and at the end of the 6-week study, including anthropometry (height, weight and waist circumference), body composition (body fat, abdominal fat and fat-free mass using Dual-energy X-ray absorptiometry (DEXA)) and blood tests to measure levels of two kinds of hormones known as adipokines (irisin and omentin), blood glucose, insulin and blood fats.

Irisin is a hormone produced during exercise that plays a role in metabolism and thermoregulation (body temperature). However, higher levels have been found in people who are overweight compared to those of healthy weight. Omentin is a hormone produced by visceral fat tissue (fat around the organs) which is associated with metabolic risk factors like obesity, insulin resistance, and type 2 diabetes.

After six weeks, the men in the combined diet and exercise group had significant reductions in irisin (41%) and LDL cholesterol levels (14%) and reductions in body fat (14%) and abdominal fat (31%). The exercise only group also had some beneficial changes in body composition, but less than the combined diet and exercise group, and a significant reduction in insulin levels. There were no significant changes in omentin levels in either group. Fat-free mass didn’t change significantly in any of the three groups, meaning that the combined diet and exercise group reduced their weight, body fat and abdominal fat while maintaining lean body mass.

The low-GI, high-protein diet led to an increase in fibre intake and a reduction in energy intake, resulting in a greater energy deficit in the combined group compared to the exercise only group. The men in the diet and exercise group also reduced their intake of fat and available carbohydrate and increased protein intake compared to baseline.

The researchers conclude that combining exercise with a high-protein, low-GI diet is more effective for improving body composition and metabolic parameters in men with abdominal obesity than exercise alone. The dietary changes, including increased protein and fibre intakes and a reduction in energy intake, contributed to the positive outcomes.

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