By Marc Sorenson, EdD, for safe sun exposure…
There is an alarming increase in obesity In the United States. Obesity is determined by a measurement called Body-mass index (BMI) which compares a person’s height with his weight and uses a mathematical formula for its calculation. To quickly calculate your BMI, go to this website: https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm. A BMI less than 24.9 is considered normal; 25-29.9 overweight; 30 and over obese, and 40+ extremely (or morbidly) obese. Since the early 1960s the prevalence of obesity among adults more than doubled, increasing from 13.4% of adults in 1960 to 37.5% in 2010. We obviously have a severe problem, with two in three adults now either overweight or obese.
There is little doubt as to the cause of obesity. We lack exercise, eat high-calorie junk foods and have moved away from sun exposure, this due to indoor living and a misguided fear of skin cancer. Most people would not put sun exposure in the list of causes, but research shows that it may play an important part in this increasing plague.
Marching in lockstep with the increase in obesity is an increase in type-2 diabetes and metabolic syndrome, which is defined as group of disorders (high blood pressure, abdominal obesity, high cholesterol, high triglyceride levels, low HDL levels and insulin resistance) that are linked to increased risk of cardiovascular disease and type 2 diabetes. This was the conclusion of a recent review on the influence of sun exposure on these conditions: “Overall, emerging findings suggest a protective role for UVR and sun exposure in reducing the development of obesity and cardiometabolic dysfunction.”
Other research has led to similar conclusions. A recent study from Northwestern Medicine demonstrates that timing and intensity of light correlate with body mass index (BMI). This research showed that exposure to bright morning light was directly related to BMI. After adjusting for confounders such as diet, exercise and sleep timing, it was determined that very early sun exposure correlated remarkably to lower BMI; even when light intensity was equal at different times of the day, those who received the earliest bright light had lower BMI. In fact, for each hour later in the day that the light exposure occurred, BMI increased by 1.28 units. This fact is exceptionally important, since a person who has a BMI of 25 (upper ideal range) could approach 30, or obesity, simply by the habit of sun exposure later in the day, i.e. 10:00 AM rather than 6:00 AM. The authors of this research suggested that the mechanisms involved in weight control by early light exposure could be the following: (1) resetting the circadian rhythm (internal clock), (2) the greater quantity of blue light in morning sun and (3) effects on melatonin production. Whatever the mechanisms, we now know that early-morning sun is important to weight control. It may also be important to other health issues.
Another scientific paper was recently published that “sheds more light” on the subject of obesity. This research was conducted on mice that were placed on a high-fat diet and then exposed to non-burning ultraviolet radiation (UVR) during a three-month experiment. The mice, without the benefit of UVR, would have been expected to gain weight rapidly, but when they were exposed to UVR, the weight gain was impressively reduced; the UVR treatment achieved 30-40% less weight gain, compared to the expected weight gain with the high-fat diet. The quantity of UVR exposure to the mice was proportionally equal to the quantity of sun exposure that a human would be exposed to by standing in the sun for ten minutes at noon.
So add sun exposure to the list of aids for obesity. Just be safe and do not burn. Let’s learn to live off the fat of the land but not be part of it!
 Gorman S, Lucas RM, Allen-Hall A1, Fleury N, Feelisch M. Ultraviolet radiation, vitamin D and the development of obesity, metabolic syndrome and type-2 diabetes. Photochem Photobiol Sci. 2016 Dec 23. doi: 10.1039/c6pp00274a. [Epub ahead of print]
 Reid KJ, Santostasi G, Baron KG, Wilson J, Kang J, Zee PC. Timing and intensity of light correlate with body weight in adults. PLoS One 2014;2;9(4)
 Geldenhuys S, Hart PH, Endersby R, Jacoby P, Feelisch M, Weller RB, Matthews V, Gorman S. Ultraviolet radiation suppresses obesity and symptoms of metabolic syndrome independently of vitamin D in mice fed a high-fat diet. Diabetes. 2014 Nov;63(11):3759-69