| Leptin leapt into the headlines when it was identified | | | | to think that fat people might also lack leptin, and |
| in 1995 as a protein that triggers weight loss in mice. | | | | that it could make them lose weight. But it was not |
| Leptin (the Greek term for thin) is a hormone | | | | so. Scientists found that most fat people had lots of |
| released by your fat cells. When you lose fat, leptin | | | | leptin, and giving them more had little effect. (The |
| levels drop and when you gain fat, leptin levels rise. | | | | New York Times 26/11/2002). |
| Recent research into leptin has revealed what is likely | | | | Researchers at the Oregon National Primate |
| to be very important in the control of appetite, | | | | Research Center conducted a study in mice involving |
| weight loss and the regulation of body weight. | | | | two separate groups that were fed high-fat and |
| Advances in leptin research and its role in the control | | | | low-fat diets. The high-fat diet group developed |
| of obesity would lead to reductions in diabetes, | | | | symptoms of diabetes and obesity while the low-fat |
| coronary heart disease and many forms of cancer, all | | | | diet group did not. The researchers tested cells which |
| of which are increased in obesity. | | | | conduct nerve impulses and found the cells behaved |
| American adults are overweight and more than 30 | | | | as if there was no leptin present, even though levels |
| percent are obese. Currently 50 million Americans | | | | were 40-times higher than in normal mice. (Cell Metab. |
| suffer from metabolic syndrome - a disease | | | | 2007 Mar;5(3):181-94). |
| associated with obesity and encompassing coronary | | | | This is due to obese people becoming resistant to |
| artery disease and type 2 diabetes. | | | | leptin's signal. When the brain fails to sense the leptin |
| Leptin affects our weight and our appetites. Levels | | | | hormone's signal correctly it thinks that more fat is |
| of leptin rise just before a meal and fall when people | | | | required, even though we have enough, and fat |
| are full. It is now known that leptin not only can | | | | begins to accumulate while metabolism slows down. |
| affect the chemical responses that affect how | | | | Some scientists think that either leptin is not |
| hungry you are but also can affect the wiring of your | | | | transported through the blood-brain barrier properly |
| brain. | | | | or the brain is not interpreting the signals properly. |
| Scientists are interested in whether leptin may be | | | | With the regular discovery of hormones involved in |
| manipulated to help people, especially overweight | | | | regulating body weight it is a diverse and rapidly |
| people, to lose weight and not put it back on. They | | | | expanding field. |
| know that leptin is released by fat cells and tells the | | | | My own research of the literature has revealed to |
| brain how much fat is on the body. Once leptin has | | | | me some dietary factors that block leptin from |
| been secreted by your fat cells, it travels to the | | | | crossing the blood-brain barrier and interfere with |
| hypothalamus. This is the part of your brain that | | | | leptin signaling. In addition, there are foods/methods |
| controls eating behavior. | | | | that correct these problems. I will discuss these |
| Defects in leptin signaling leads to obesity, overeating, | | | | issues in due course. |
| and decreased energy output. | | | | If this article is reproduced please ensure the link to |
| Normally, when leptin levels in the blood go up, the | | | | my website is kept live. If you can't see the links |
| brain signals us to stop eating. But since obesity isn't | | | | hover your mouse over the words in the bio box. |
| the result of a lack of leptin, it is a lack of response | | | | References |
| to leptin, and obese individuals tend to have more | | | | Enriori PJ, Evans AE, Sinnayah P, Jobst EE, |
| and larger leptin-producing fat cells than thinner | | | | Tonelli-Lemos L, Billes SK, Glavas MM, Grayson BE, |
| people, their leptin levels increase substantially with | | | | Perello M, Nillni EA, Grove KL, Cowley MA. |
| every pound of additional weight gain. This is | | | | Diet-induced obesity causes severe but reversible |
| illustrated below. | | | | leptin resistance in arcuate melanocortin neurons. Cell |
| Mice lacking leptin ate voraciously and grew | | | | Metab. 2007 Mar;5(3):181-94. |
| enormously fat; leptin injections made them stop | | | | If this article is reproduced please ensure the link to |
| eating and slim down. The discovery led researchers | | | | my website is kept live. |