The weight of an animal is not under conscious control. This would be a bad evolutionary design. The case that anorexia (extreme weight loss) is caused by vitamin deficiency is strong. Read more here. Young women who take vitamin supplements do not become anorexic. There is also a strong case to be made that vitamin deficiency is an important cause of obesity. Read more here and here.

Weight is largely controlled by the subconscious mind. The subconscious mind, in response to the environment, selects a target weight within the range of normal. Regular intense aerobic activity lowers the target weight.

Vitamin D has been hypothesized to be involved in weight regulation. It has already been proven that vitamin D has hormonal functions. I believe it is only a matter of time until a role for vitamin D in weight regulation is proven.

Vitamin D is produced when cells just beneath the surface layers are exposed to ultra violet radiation from the sun. Regulation of sun exposure is yet another important body function that is not under conscious control. Regular sun exposure causes skin pigmentation that reduces the amount of sunlight penetrating the outermost layers of the skin. Absence of regular sun exposure causes the skin to loose pigmentation. The available evidence suggests that evolutionary selection acts rapidly to optimize skin color in response to the local environment. All human peoples migrating from the equator to the poles evolved white skin within generations. This is a powerful argument for paying close attention to vitamin D.

Since the skin produces vitamin D, subconscious signals encourage sun exposure. Most people enjoy the feeling of being out under the sun, and are attracted outside when the sun shines for the first time after a number of cloudy days. There are equally powerful subconscious and conscious feelings preventing overexposure to the sun.

In modern times, consumer services have emerged that cater to the feelings that draw us to the sun. Sunblock lotions allow us to lie in the sun indefinitely, enjoying the luscious warm feelings (unlike any other kind of warmth). Tanning salons also allow endless hours of warmth and create a healthy-looking tan. Unfortunately, both sunblock lotions and tanning lamps block the production of vitamin D, and must be used with caution.

Intense excersize indicates a ecological need for fast motion. Fast motion is facilitated by lower weight. It makes good sense that the subconscious weight control system would adjust down the set weight in response to even short bursts of intense exercise (research indicates that just 10 to 20 minutes, two or three times a week may be sufficient).

We are in the midst of a modern obesity epidemic that has been clearly linked to the western lifestyle. Sun avoidance is part of that modern lifestyle. We dress for work, work indoors, and increasingly play indoors. More and more of life occurs after sunset plugged into the network or watching TV or movies. Airconditioning drives us indoors when it is hot, and heating drives us indoors when it is cold. As a result we are in the midst of a vitamin D deficiency epidemic. It therefore also makes good sense to link obesity with vitamin D deficiency.

It is difficult to optimize vitamin D by taking supplements. Vitamin D supplements cause side effects. Read more here. Higher doses of vitamin D can be gotten from the sun without risk of side effects. If it isn’t possible to get into the sun, vitamin D supplements work, but require vigilant attention to side effects.

Sun and exercise are enjoyable, safe, and effective components to prevent and treat obesity. As with many vitamin deficiency diseases (anorexia is a particularly painful example), obesity is more easily prevented than cured. It is much more effective to instill these healthy habits in children and adults of a healthy weight than to instill them in already obese adults. Don’t let the failure of this advice to work for already obese adults to convince you that these common sense habits aren’t important for preventing obesity.

So, think “RUN and SUN” for the prevention of obesity. There is much to gain and almost nothing to lose by adopting these healthy habits.