Low glycemic meals produce favorable leptin and insulin responses, resulting in lower food consumption

Low glycemic meals promote a post-meal environment that is favorable for reduced food consumption. This may be an advantage in the control of obesity and related disorders, including insulin resistance and type 2 diabetes.

Low glycemic meals produce favorable leptin and insulin responses, resulting in lower food consumption.

In a recent study, metabolic effects of meals with varying glycemic index (GI) were evaluated. In a group of healthy volunteers, glucose, insulin and leptin responses to two contrasting breakfast cereals were measured. Leptin is a hormone produced by fat cells that indicates the degree of hunger to the hypothalamus of the brain. Lower leptin levels trigger a sense of satiety and decreased hunger.

Meals were provided on two separate occasions in random order after a 12-hour overnight fast, and consisted of 50 g of available carbohydrate from either Corn Flakes (Kellogg's), or Fiber One (General Mills). Blood samples were obtained at rest, and 30, 60, 90 and 120 min after eating. The GI was calculated from the glucose response to the test meal normalized against a 50 g oral glucose load.

The average GI for Corn Flakes was 125 and 49 for Fiber One. These meals were classified as high GI and low GI, respectively, and were significantly different from each other. The insulin response following the low glycemic meal was significantly reduced compared to the high glycemic meal. The high glycemic meal significantly suppressed circulating leptin levels compared to the low glycemic meal.

Lower insulin response and higher circulating leptin levels suggest that low glycemic meals promote a post-meal environment that is favorable for reduced food consumption; this may be advantageous in the control of obesity and related disorders, including insulin resistance and type 2 diabetes.

Ann Nutr Metab 2007 Dec 10;51(6):512-518

Childhood overweight and obesity are still a concern

A recent Australian survey indicates that childhood overweight and obesity are still a concern. In 2007 The Australian National Children’s Nutrition and Physical Activity Survey assessed the food and nutrient intake, physical activity levels, and the weight, height and waist circumference among randomly selected children aged 2–16 years. Key findings from the survey released recently indicate that:

• 72 per cent of children surveyed were at a healthy weight; 17 per cent of boys and girls were classified as overweight; 6 per cent were obese; and 5 per cent were found to be underweight.
• The children surveyed demonstrated a low level of observance of the Dietary Guidelines for Children and Adolescents in Australia.

Poor dietary habit is still a great concern for our children, especially for the 14-16 year olds.

• The proportion of children meeting the guidelines for fruit intake (1–3 serves per day) and vegetable intake (2–4 serves per day) declined with age.
• 61% of 4–8 year olds consumed adequate fruit (excluding juice), compared to only 1% of 14–16 year old boys and girls
• Only 22% of 4–8 year old children and 5% of 14–16 year olds met the dietary guidelines for vegetable intake.
• Saturated fat intake contributed approximately 13–14% of the children’s energy intake, higher than what is recommended in the Dietary Guidelines (saturated fat should contribute less than 10% of total energy intake).
• Some micronutrient intakes such as calcium, sodium and magnesium are likely to be problematic, particularly for the 14–16 year olds who were the least likely to meet the recommended intake.

Approximately 69% of boys and girls aged 9–16 surveyed accumulated at least 60 minutes of moderate to vigorous physical activity on most of the days surveyed. The average time spent doing moderate to vigorous physical activity decreased with age. Only 33% of the children aged 9–16 years met the recommendations for screen time in the National Physical Activity Guidelines (no more than two hours of non-educational screen time each day).

Result from this latest survey reinforced the value of establishing healthy eating and regular exercise patterns for children’s health and wellbeing. The foundations for optimal health begin at early age from childhood, and progress day by day. Establishing sound nutritional foundation and tackling overweight and obesity, is without any doubt, very important for every stages in life.

Gastroenterology. 2008 Oct;135(4):1163-7.