A lean body devoid of fat may be more significant in determining lifespan than a calorie-restricted diet, according to a new study of genetically altered mice.
The mice in the study were able to eat whatever they wanted and still stay slim because their fat tissue had been altered so it could not respond to the hormone insulin. Insulin helps to move sugar from the blood into the body’s cells and also helps fat cells to store fat.
Researchers altered the insulin receptor gene in the fat cells of lab mice, and since insulin is needed to help cells store fat the mice had less fat and were protected against obesity.
The altered mice ate 55 percent more food per gram of body weight than normal mice, yet had 70 percent less body fat by the time they reached 3 months of age.
Moreover, the altered mice lived 18 percent longer than normal mice, and after three years all of the normal mice had died, but one-quarter of the altered mice were still alive.
Previous studies have shown that a calorie-restricted diet can extend the lifespan of everything from yeast to mammals. One theory for why this occurs is that eating less produces fewer chemical by-products, known as free radicals, which can damage cells. However, the current study suggests that leanness may also play a role in promoting longevity.
The findings could open the possibility of a new drug that would fight obesity, and related illnesses like type 2 diabetes, by blocking insulin receptors in fat tissue. The drug would need to be targeted to fat only, however, as a loss of insulin sensitivity through out the body results in type 2 diabetes, researchers noted.
Science January 24, 2003;299:572-574
It appears that leanness, not food restriction, is a key contributor to a long life. The elegant study from Harvard published in a prestigious science journal, Science, confirms that insulin is the major mechanism through which this result is mediated.
Most health care practitioners are not aware of the profound influence that insulin has on health. Many basic science researchers, however, realize this and that is why you will see more and more studies like the one above. A firm appreciation of insulins role in health is one of the most important things you can do to normalize your health on a physical plane.
If you have clinical signs of high insulin levels, such as:
- Elevated Weight
- High Blood Pressure
- Elevated Cholesterol
- High Fasting Serum Insulin Levels (above 5)
Then it would be especially wise to consider avoiding all grains and sugars until those problems normalize. If you know your body is geared toward requiring more carbs (from discovering your metabolic type), it is highly likely that grains can be re-introduced into your diet in a limited quantity at a later diet. To help in the process of understanding these principles and avoiding grains and sugars, I urge you to consider reading my new book, which also includes a basic test to help you determine your nutritional type.
If you have not read Dr. Rosedales insulin article below, I would strongly recommend doing so. Dr. Rosedale is the physician who helped me appreciate the importance of insulin in 1996. I have had many patients share with me how helpful his article was in understanding insulin.