In the United States, the diet and weight loss industry is nearly a $61 billion enterprise. In some instances, its purveyors are modern-day equivalents of traveling snake oil salesmen. For a case in point, the new Hollywood diet craze—the HCG fat-burning supplement—promises that with daily sublingual applications of a couple of drops of their product, people can burn up to 2 pounds of fat per day. HCG is a hormone (human chorionic gonadotropin), and as an injection it is prescribed for some cases of female infertility and other medical conditions. There have been studies into its efficacy with regard to weight loss, but with negative results. Losing weight with the Hollywood version has nothing to do with the supplement and everything to do with its recommended caloric restrictions.
Another popular weight loss supplement right now is raspberry ketones. This miracle supplement, advertised as a “fat burner in a bottle,” is being promoted all over the radio and was even seen on The Dr. Oz Show. The simple fact is that the existing evidence does not support weight loss claims associated with this supplement. The 2 studies that have been conducted were small animal designs that used only male mice. To date, neither study has been independently verified, nor have their results really been earth shattering.
Obesity rates in America are quickly reaching pandemic proportions. Coupled with higher associated medical costs that now surpass smoking, they are simply unsustainable. According to recent statistics from the CDC, the proportion of obese adults has hit a staggering 35.7% of the population. Since 1980, there has been a 3-fold increase in the prevalence of obesity in children and adolescents, which now stands at 17% (ages 2 to 19 years). Type 2 diabetes, which is traditionally an adult-associated disease, can be seen in an increasingly younger population. In 2004, a 5 year old weighing in at about 90 pounds won the distinction of the world's youngest child with type 2 diabetes, a distinction previous held by a 9-year-old French child.
In an effort to curb childhood obesity, and based on recommendations from the Institute of Medicine, the USDA released guidelines to improve the nutritional content of school lunches. This issue was quickly politicized and called burdensome for agribusiness. Heated debates roared in congress about limits on sodium content, whether or not pizza was a vegetable, and how often French fries can be served. Ultimately, the accepted guidelines are something we can be proud of: pizza is a vegetable and you can eat all the fries you want.
We've gone through the looking glass. Up is down, day is night, and pizza is a vegetable. Although to be fair, pizza was previously classified as a vegetable and the new guidelines were an attempt to change that. There were some beneficial changes; for instance, incorporating whole grains into lunches, lowering the sodium and trans-fat content, and upping the amount of fruits and vegetables.
Currently, what is really known about diet and weight loss? The answer is quite a bit. However, misinformation and trendy diets have so permeated our collective unconscious that differentiating quality information from misinformation has become difficult. For instance, in many circles it is generally accepted that carbohydrates turn into fat. That concept is at best technically true but under normal circumstances it doesn't happen. De novo lipogenesis (converting carbohydrates into fat) does occur but only under an extreme condition of excessive overeating and the total amount created is minute. Under this specific condition, consuming more daily calories (about 2 to 4 times higher than recommended), with a majority of them coming from carbohydrates, enables de novo lipogenesis. Our bodies are constantly using carbs and fats for energy but in varying proportions tied to aerobic output (eg, sitting, walking, running, sleeping). What generally happens when a large quantity of carbohydrates is consumed is that our bodies switch from utilizing a mixed energy source (carbs and fats) to using glucose as a primary source of energy until levels normalize. Of course, during this period when glucose is the primary fuel, fat won't be utilized.
Another popular misconception is that people on low/no-carbohydrate diets tend to lose more fat (of course, fat cells aren't lost, they shrink or swell). Typically in the absence of glucose and glycogen, you will utilize fat as a primary fuel source. Initially when someone stops consuming carbs, and the glycogen reserves become depleted, it is followed by a loss of water weight. This only appears to be a larger reduction in weight than someone on a more complete diet, but the water weight will be gained right back. Some foods are obviously better than others because they supply nutrients, but with regard to utilizing energy, a calorie is a calorie.
The greater body of scientific evidence shows no real efficacy associated with different diet types (eg, low carb or low fat), assuming similar caloric intake and expenditure. However, some studies suggest that potential differences in weight loss may be more closely associated with satiation and palatability. If you feel full or satisfied after a meal, you tend to consume less during the next meal. Typically, proteins fill you the most, followed by carbohydrates; fats are at the bottom. Palatability also may have a major influence in overeating regardless of how full you may feel. When people eat a meal that is very tasty, regardless of what kind of macronutrient it contains (eg, protein, fat, or carbs), they tend to eat more during their next meal.
When it comes to dieting and weight loss, common sense is king and we are all subject to the same laws of physics. For everything to remain constant within a system, the energy going into that system must exactly match the energy going out. So the simplest way to lose weight is to take in less energy (in calories) than you expend.
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