Hormones play a part in body weight regulation and also regulating food intake. Some evidence suggests that regulation of body weight and intake occurs on both a short and long term basis. Short term regulation controls the consumption of food from meal to meal. Long term regulation is controlled by the availability of adipose or fat stores and hormone responses.
Short term regulation is concerned with the hormones that influence hunger, appetite and satiety (hunger suppression). Between meals when the stomach is empty, a recently identified hormone, ghrelin is released and sends a “hungry” message to the brain. This message stimulates the release of neurotransmitters or chemicals which increase hunger. As a meal is consumed, ghrelin production decreases rapidly and hunger is reduced.
After a meal is consumed other hormones are released which regulate the urge to eat. Cholecystokinin (CCK) a hormone which is produced in the small intestine increases during and after a meal. CCK production following a meal reduces appetite and promotes satiety (suppresses hunger). Another recently identified hormone, PYY produced in the small intestine suppresses appetite for up to 12 hours. The amount of PYY produced is proportional to the energy or the caloric content of the meal.
Long term regulation involves a feedback mechanism in which a signal from the adipose or fat stores promotes a reduction in hunger. Leptin, is a hormone produced by the fat cells. The more full the fat cells the more leptin it produces and sends a “satiety” message to the brain. This message then stimulates the release of neurotransmitters or chemicals which suppress hunger. The effect of leptin, then, is to control the level of stored body fat. As the level of body fat decreases, the amount of leptin produced decreases and hunger is not supressed as much. As the body fat level increases, the amount of leptin increases and energy or caloric intake is reduced. This mechanism works well in people with a healthy weight. In overweight individuals, however, this mechanism is defective as the message to the brain is not processed appropriately and as a result increased leptin levels do not suppress hunger.
However, there are many other factors that influence energy intake and body weight including:
· Consuming more food through larger portion sizes
· Consuming food and drink higher in energy (kilojoules or calories)
· Being sedentary or physically inactive
· Following restrictive weight loss or fad diets
Successful weight management requires a life-long commitment to a healthy lifestyle, which includes eating healthy foods and keeping physically active in a way that is both sustainable and enjoyable. An Accredited Practising Dietitian can provide expert dietary advice on weight management which is tailored to indiviudal needs.
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