Insulin allows cells to take up sugar. Fat cells and muscle cells are big users.
Brain cells and liver cells don’t use insulin so they take sugar out of the blood stream if it is available. Insulin stimulates the liver to produce fats from available sugar. First glycogen is stored, then as that rises to a maximum, fat is produced. The fat is sent into the blood.Insulin also suppresses the breakdown of fat. Fat cells are stimulated to produce glycerol from sugar molecules which combine with the circulating fatty acids to produce triglycerides. Triglycerides are stored, swelling the fat cells. Insulin encourages the body to burn sugar and keep fat. Fat that is consumed and circulating can also be stored.
Type I diabetes involve the destruction of insulin producing cells, usually by an autoimmune process. It is treated by insulin replacement. Uncontrolled Type I diabetics can become painfully thin if their disease gradually reduces insulin production.
Insulin and Obesity
Type II diabetes is insulin resistant, involving a reduction of insulin receptors. Insulin is often at a normal or high level. This can be caused by a diet that is high in simple sugars which maintains a high blood sugar level. Over time, the receptors decrease in response to excessive sugar. Muscle and brain cells can only consume a limited amount of sugar. Liver and fat cells are not so limited. With abundant sugar and plenty of insulin, they breakdown the sugar into fat and store it. Not everyone develops diabetes from excessive sugar intake but many do. Some people simply get fat. Drugs that increase circulating insulin to decrease blood sugar can also stimulate the liver to create fat and stimulate fat cells to store it. Excess insulin creates fat. Excess consumed sugar creates fat. Excess consumed fat in the presence of insulin causes fat cells to get bigger too.
There can be imbalances in the control systems that lead people to become obese while consuming otherwise healthy diets. Bad choices are not the only reason. Rising levels of obesity and clinical experience would lead us to suspect that predominantly, fatness is caused by choices.
Our paleolithic ancestors ate perhaps 10 to 15 pounds of simple sugars per year. Americans commonly exceed 150 pounds of sugar per year. Our metabolisms weren’t built for this.
The question becomes, “Have people been lead to make the poor choices?”
Photo by Dave Hutt, www.dmddigitalphoto.com