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Obesity epidemic: more than just overeating
The gradually increasing prevalence of obesity in the United States began approximately 50 years ago and has already had major effects on our health and the cost of health care. The major — but not the only — reason for the epidemic of obesity is an increased food intake. In the past 40 years, per capita calorie intake has increased by 20% (or 450 calories) and utilization of home-cooked meals has decreased as the utilization of fast food and full-service restaurants, with larger portions, has increased. Currently, 20% of our calorie intake comes from these restaurants where the average adult now eats 5 times per week. However, there may be other factors.
Fructose plus corn syrup
Before 1980, although fructose containing corn syrup was available and cheaper, it was seldom used because sucrose derived from sugar cane was preferred. In 1980, Hurricane Allen hit the Caribbean and wiped out the sugar cane crop so that the “homegrown” corn syrup product had to be adopted. The expanded utilization of the cheaper corn syrup, which is stable, easily produced and can be efficiently used in multiple foods including sodas and fruit juices, caused the price of sugar cane to drop so that the total global consumption of sugars —and therefore calories — increased.
Fructose is 73% sweeter than sucrose. While the intake of sucrose stimulates the secretion of insulin, the uptake of sugars by muscle and storage of sugars as animal starch (glycogen) in the liver, fructose —especially in large quantities— initiates fat formation in the liver and muscle (causing resistance to the action of insulin) and in the pancreas (causing a decrease in insulin production and increasing the possibility of developing diabetes). In addition, fructose results in excess production of uric acid (a chemical that causes gout and kidney stones), and initiates changes such as inflammation that result in increases in cardiac events.
David S. H. Bell
Fructose is not efficient in suppressing the appetite because hormones such as leptin that suppress the appetite are not increased and hormones such as ghrelin that increase appetite are not suppressed. As a result, even a high fructose intake does not stimulate the centers in the brain, which when stimulated decrease the intake of food.
Changes in diet, diet drinks
Another possible cause of the obesity epidemic is the utilization of diet drinks. Normally when something sweet is consumed, the body expects calories, particularly sugar calories, to accompany or follow the food or drink. When diet drinks are utilized, there is an even greater expectation, but the calories do not follow. The absence of this “payoff” results in overeating and weight gain rather than the weight loss, which would be expected from changing to no-calorie drinks.
The obesity epidemic may also be caused by a diet high in fat and sugar, which alters the composition of the 100 trillion bacteria that inhabit our intestines. In a healthy state, we have a symbiotic (mutually beneficial) relationship with these bacteria, but exposure to this diet may lead to dysbiosis (a harmful relationship), in which bacteria move from the exterior to the interior of the body and increase not only inflammation but also the absorption of calories.
This bowel “porosity” has been shown to be worsened by vitamin D deficiency, the frequency of which is increased with established obesity since vitamin D, a fat soluble vitamin, is taken up and sequestered by the fat cell. Before obesity becomes irreversible it is possible that the use of probiotics, which change the composition of the gut bacteria or correction of vitamin D deficiency, may strengthen the barrier to bacterial invasion. Interestingly, bariatric (weight-loss) surgery has been shown to positively alter the composition of the gut bacteria, which could be a major factor in the considerable success of this very invasive surgery.
Traditional weight-loss programs with or without anti-obesity drugs rarely achieve an adequate or permanent weight loss. Research is urgently needed to find medications or a less invasive surgical procedure with which to treat obesity so that the obesity epidemic, which has the potential to not only negate the gains in decreasing cardiac events achieved with modern therapies such as cholesterol and blood pressure-lowering drugs but also so bankrupt the health care system, can be repaired.