Many 'fad' diets become widely popular for a short period of time, only to fade out. Although some fade from popularity due to being ineffective, some merely lose the public's interest. Judging their nutritional merit can be especially difficult given that most diet proponents locate medical professionals to back up their work. Examples of such fads include the grapefruit diet, low-fat diets, and Atkins.
Many fad diets advocate a specific technique (such as eliminating a certain food, or eating only certain combinations of foods) in conjunction with the basic idea of balancing energy in versus energy out, the goal being to accelerate weight loss. Some ignore traditional science altogether.
Grapefruit diet
On the grapefruit diet, the consumption of grapefruit with each meal was said to increase the metabolic rate, burning fat and enabling rapid weight loss. The grapefruit diet was eventually found to be entirely ineffective.
Low-fat diets
Low-fat diets were popular during the 1980s and 1990s, encouraging people to eat foods low in fat (or without fat altogether) and instead eat foods high in carbohydrates. The diet worked on the principle that of the three main macro-nutrients (fat, carbohydrates and protein), only fat was the one which would cause weight-gain. This failed as people ended up eating excessive amounts of low-fat foods rich in refined carbohydrates such as sugar. Some low-fat dieters even gained weight due to the calories from the carbohydrates.
Atkins
Atkins encourages limited carbohydrate intake, and consuming more meats, nuts, unsweetened fruits, berries and green vegetables. This causes rapid weight loss for many people, although it continues to be disputed whether this is due to a metabolic advantage of ketosis, as Atkins claimed. Some of the initial rapid weight loss is due to depletion of glycogen stores in the liver. Glycogen must be associated with several times its weight of water in the body. Low carbohydrate diets have been shown to reduce the fasting levels of triglycerides. Elevated triglycerides are a demonstrated risk factor for heart disease and also account for part of the risk of low density cholesterol due to their associated worse particle size profile.
Any successful diet for losing weight will cause some ketosis, since ketones are produced when the body is using fat energy to synthesize glucose (gluconeogenesis) during the long overnight fast (sleep). Elevated levels of fasting triglycerides (TGs) are the product of de novo lipogenesis (synthesis of new fats) from glucose substrate. If the liver was engaged in gluconeogenesis from fat, and synthesizing fat from glucose at the same time, this would be a futile cycle, and a fantastic way to waste energy and lose weight. For most of human history, it has been important to survival to avoid such inefficiency, so the body switches modes to avoid this futile cycle. This explains the dramatic reductions in fasting TGs seen in many low carbohydrate dieters.
Are they dangerous?
As with most trends and fads - the idea is to not overdue it. Most fad diets are really meant for short-term usage and not for a life-long eating change. Another factor to consider is the driving force behind your decision to choose a "fast-track" approach to your weight loss and not a tried and true method. What is your motivation to lose the weight? To fit into a dress? To be healthier? To satisfy a partner? To like what you see in the mirror? You may find that your reasoning is causing you to make poor choices when it comes to your health and well-being. And no matter what diet you choose, you could be setting yourself up for serious fall.
Lisa Angelettie, M.S.W., is a psychotherapist, author, and an online advice expert. She has been helping people make smarter life choices since 1998. Visit her for Advice & Counseling, or take a free Depression Screening today.
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