Control of Eating
It Is estimated that globally 4.7 million people die prematurely as a result of obesity related problems. In the USA 36% of the population are obese. (https://ourworldindata.org).
Obesity is measured simply as BMI, Body mass index, which is a measure of weight-over-height, and has been used as a general indicator of weight-related health risks. However BMI measures can overestimate the number of overweight individuals. For example, muscle mass can increase bodyweight, resulting in athletes or individuals with a high muscle mass percentage being deemed overweight, even if they have a low or healthy level of body fat. Similarly comparisons between groups can also be misleading. Muscle and bone density tends to decline as we get older; this means that an older individual may have a higher percentage of body fat than a younger individual while having the same BMI. Women tend to have a higher body fat percentage than men for a given BMI. But it can be a useful measure when looking at trends globally and between countries.
As a general rule it is noticeable that the more affluent countries tend to be the more obese. However within countries there has been a stark change over the years of poorer households disproportionately having a greater incidence of obesity. The Health Survey for England 2017 estimates that 28.7% of adults in England are obese and a further 35.6% being overweight but not obese. The UK is the most obese country in western Europe, with poorer households exhibiting a greater degree of obesity.
Physiologically the body responds to a meal in a fairly predictable manner. As carbohydrates are broken down, there is a rise in glucose levels within the blood and Insulin is secreted as a result. Following the ingestion of a meal the levels of Cholecystokinin CKK rises. CKK is a hormone which is secreted by cells in the duodenum and stimulate the release of bile into the intestine and also the secretion of enzymes by the pancreas, which then begin to digest the food. CKK delays gastric emptying, that is, partially digested food within the stomach, and is thought to play a role in satiety, the sense of being full. Insulin potentates the role of CKK. The role of Insulin is less effective when a high fat diet is consumed
Interestingly Glucagon also produces the effect of satiety, along with Calcitonin which regulates Calcium levels in the body. Glucagon is released by the pancreas when the levels of glucose are low, and it stimulates the liver to break down stored glucose in the form of glycogen. This may be as a response to a greater need during exercise, but it does not stimulate hunger.
When glucose levels drop along along with insulin levels, Neuropeptide gamma is activated and stimulates hunger. Low Serotonin levels have also been associated with carbohydrate cravings.
Somatostatin, which is also found in the digestive tract inhibits the secretion of both insulin and glucagon, in conjunction with inhibiting the release of the growth hormone and thyroid stimulating hormone, resulting in suppressing hunger.
Body fat (adipose tissue), is now considered an active endocrine organ responsible for the synthesis and secretion of several hormones. One particular hormone that has been studied is Leptin, which, when secreted from adipose tissue, inhibits the feeding behaviour of rodents. Curiously obese individuals tend to have more Leptin in their bloodstream than their leaner counterparts. This has led to the idea of Leptin sensitivity.
Considering that Obesity leads to Insulin sensitivity resulting in the individual not being able to utilise the glucose within the bloodstream, and being therefore unable to incorporate the glucose into into the cells for the use of energy, energy needs of the individual would still be required. Leptin’s continual release may be a result of this imbalance.
Research is still ongoing as regards the various systems involved in regulating feeding and balancing energy needs, however it appears that the body is more sensitive to the energy needs of the body as regards to feeding, rather than having a tight control over of when to stop. It is also noticeable that we often misinterpret the sensation of dehydration as a sign of hunger.
Generally, particularly when food is plentiful, other factors will also stimulate the desire to eat. We do not just eat to satisfy hunger but are stimulated by the sight and smell of food, and its pleasurable aspects. We are more drawn to foods which are sweeter and have a higher fat content, with very little fibre or water. That is, foods which are considered to be of higher density, but lower in nutritional value. Another factor that stimulates overeating is variety. We tend to eat more when there is a greater variety of sensations. For many, food choices are also based on cost and/or convenience. Cheaper and convenience foods tend to be higher in sugar and fat. This may be the major contributing factor as to why we now see differences in obesity levels between lower and higher economic groups.
Obesity is associated with insulin resistance, resulting in cells of the body not being able to take up glucose. The result being that excess glucose remains in the blood, There is also an increased level of fatty acids as Insulin inhibits lipolysis (fat breakdown), this state leads to greater degree of inflammation within the body.
How to decrease Adipose Tissue