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Adipokines and Cytokines of Fat Burning: Small But Important Molecules

Most people have been getting dietary advice all wrong. Eat less, move more works only for some people for a period of time, but it is not solid long-term dietary advice. Low carbohydrate diets again and again show greater weight loss, increase in HDL, reduction in blood pressure, resolving diabetes and metabolic syndrome and also reduce risk for diabetes, cardiovascular disease, and cancer in numerous studies. So why do we still give the wrong information? In the next few articles, we will look at how the body becomes fat and the best performing dietary change for weight loss: a low carb/high fat diet.

In the previous article, we took a look at the hormones of fat burning, including: insulin, glucagon, ghrelin, and others. Adipokines and cytokines are two hormone-like messengers made by fat cells. Though they are not hormones, they act similar to hormones in that they are released by cells and affect the behavior of other cells.

Adipokins — incluing leptin, adiponectin, LPL, and HSL — are secreted by adipose tissue (fatty tissue) and can play a central role in the development of insulin resistance, type 2 diabetes, and cardiovascular disease associated with obesity.

Leptin — Leptin is an adipokine made in the fat cells. Normally, leptin rises with feasting and falls in fasting. The fall of leptin signals to the brain…‘time to burn fat!’ In insulin resistance, leptin levels remain elevated. When leptin stays high, the brain thinks the person is eating, so glucagon is inhibited.

Adiponectin — Adiponectin regulates glucose and fat levels with insulin. Obese people have lower blood levels of adiponectin than normal weight individuals. Reduction of obesity increases adiponectin levels. Adiponetin enhances your muscle’s ability to use carbohydrates for energy, boosts your metabolism, increase the rate in which your body breaks down fat, and curbs your appetite. Adiponectin, the fat-burning hormone, is insulin sensitive meaning insulin levels must be low in order for adiponectin to take fat across the cell wall to burn. Low adiponectin levels are more strongly associated with the amount of visceral fat (belly fat) than subcutaneous fat (fat in the thighs or buttocks).

Lipoprotein Lipase — Also known as LPL, lipoprotein lipase is regulated by feeding/fasting, insulin, and exercise. If insulin is elevated, such as after a meal, LPL is expressed more on the fat cells than on the muscle cells, particularly if the individual is insulin resistant and eats a meal that is high in carbohydrates. LPL receptors take fat from the blood stream into the cell. If insulin levels are low, as in the case of low carb diets, the LPL is expressed more on the muscle cells than on the fat cell and the fat is more readily burned before being stored as fat.

Hormone Sensitive Lipase — Hormone sensitive lipase, or HSL, dismantles triglycerides in the fat cells to take the fat molecule across the cell wall into the blood to be burned. High levels of insulin in the body inhibits HSL from doing its job.

Once we have too much fat, we also get “angry fat” that produces inflammatory messengers (Cytokines) that increase fat storage and disease risk. We’ll take a closer look at cytokines in the following article.