By Robbie Durand, Muscular Development
Despite the protests of dietitians, the American Heart Association and political lobbyists serving the sugar and grain industries, Americans found themselves losing significant weight following low-carbohydrate diets without suffering an increase in cardiovascular risk, as was portended by many critics.
Everyone has some body fat. Healthy levels of body fat actually improve a person’s health and appearance, but excess fat tends to increase the risk of poor health and is generally viewed as unattractive in most cultures. Excess fat accumulates in different areas from person to person, though some generalities can be made. Women tend to accumulate fat in the thighs and around the pelvis (hips, buttocks and the lower abdominal “pooch”); men are more likely to deposit body fat in their midsection, providing a visual cascade of fat over the restraints of stressed belts.1 This has given rise to the descriptive terms of apple- versus pear-shaped body types.
“Apples” can include both men and women, as is easily seen by taking a quick survey of the bodies shopping at any local mall.2 Often, central fat (another term used to describe abdominal fat, both visceral— surrounding the internal organs and subcutaneous— under the skin) accumulates due to a state described as glucose intolerance or insulin resistance.3 Glucose is the scientific term for sugar in its most common form. Glucose is in nearly every carbohydrate-containing food and is the main stimulus for insulin secretion. Most lean people are very efficient in dealing with glucose, using only the necessary amount of insulin to shuttle the sugar molecules into the muscle, liver or fat cells. Actually, nearly every cell in the body has receptors for insulin, but muscle, liver and fat cells are the main targets. However, some people become resistant to the insulin signal, so the pancreas releases more of the hormone into the bloodstream in order to dispose of the sugar influx from a meal. In some cases, insulin remains high, even when the person is fasting; others have normal fasting insulin but have to release a great deal more of the hormone when food is consumed. Fasting is the state of the body when one has not eaten for several hours. Most doctors look only at the fasting glucose level— some will check fasting insulin levels as well. Only recently has the importance of insulin release with a meal been realized. Yet, this is rarely checked, as it involves a more expensive and time-consuming process than a simple blood draw.
In order to measure insulin secretion after a meal, a patient has to undergo a glucose tolerance test (GTT). To perform a GTT, a patient must arrive in the fasted state, typically first thing in the morning. It is important that no food or caffeinated beverages have been consumed. Blood is drawn to measure insulin and glucose, and then a sugary drink containing exactly 75 grams of sugar is given. Insulin and glucose levels are checked at regular intervals and the lab values are plotted on a chart.4
Research has found that the preachings of Barry Sears (founder of the Zone Diet), Dr. Robert Atkins (founder of the Atkins Diet) and others who have stressed insulin control as a major factor in weight management are in fact correct.5 Despite the protests of dietitians, the American Heart Association and political lobbyists serving the sugar and grain industries, Americans found themselves losing significant weight following low-carbohydrate diets without suffering an increase in cardiovascular risk, as was portended by many critics. In fact, it is believed that low-carbohydrate diets are at least as safe as the low-fat diets endorsed by many cardiologists, perhaps even safer and beneficial.6
However, just as fat has never been the nutritional villain suggested by well-meaning dietitians, neither are carbohydrates. For most people, absolute- or near-absolute carbohydrate restriction can impair performance and alertness; this is particularly true for athletes.7 It is important to realize that all carbohydrate-containing foods are not the same. Some dump their sugar load into the bloodstream rapidly, causing sudden fluctuations in serum (blood) glucose levels. This causes the pancreas to respond by pumping out large amounts of insulin— examples include white bread, most breakfast cereals, sugary drinks and treats (sports drinks, jelly beans). Other foods release their sugar load slowly, allowing the pancreas to deal with the sugar influx gradually by releasing smaller amounts of insulin over a longer period of time— examples of these foods include milk, yogurt and most types of beans.
How quickly the sugar from a food reaches the bloodstream determines its glycemic index. The glycemic index is touted by some popular diet plans, such as the NutriSystem Diet, endorsed by former NFL star quarterback Dan Marino. However, the glycemic index is not the complete solution to weight loss and managing insulin. The total amount of carbohydrate consumed needs to be accounted for as well— total carbohydrate content X glycemic index = glycemic load. It makes sense when you think about the situation. While a handful of Good & Plenty licorice candies have a high glycemic index, the glycemic load is less than drinking a half-gallon of milk or eating a family sized can of baked beans. A convenient chart listing the glycemic index and glycemic load of many foods is available at http://www.mendosa.com/GI_GL_Carb_data.xls based upon the seminal article published in 2002 in The American Journal of Clinical Nutrition.8
While the low-carbohydrate diets became very popular, for some, they were much more effective than a low-fat diet— others had no greater success. This led to conflicting results in many studies and confusion among the masses. Researchers speculated about the contradiction and hypothesized that individual differences in responding to the low-carbohydrate diets may be due to unique insulin responses in each person. When a high level of insulin is released after a meal, it promotes fat gain because insulin blocks the release of stored fat, promotes fat storage and causes blood glucose to plummet.9 When fats are shuttled away and blood sugar drops, hunger signals are generated and a person tends to overeat, consuming more food and eating more frequently.10 People who experience a moderate release of insulin following a meal tend to avoid the metabolic mismatch and generally experience greater success in managing their weight. Controlling the glycemic load of a meal is one way to control the insulin release after a meal. Thus, it was suggested that people who release a lot of insulin after a meal would lose more weight following a low-glycemic-load diet.
This had been shown in rat studies, with high-insulin releasing rats having greater weight gain than other rats when fed a high-glycemic-load diet but when fed a low-glycemic-load diet, their weight was the same as normal rats.11 Two short-term studies, ranging from four to six months, demonstrated that humans who release a greater amount of insulin following a meal lost more weight when placed on a high-fat diet.12,13
Thus, two groups of people were randomly placed into either a low-fat diet program (55 percent carbohydrate, 20 percent fat, 25 percent protein) or an identical program using a low-glycemic-load diet (40 percent low-glycemic load carbohydrate, 35 percent fat, 25 percent protein).14 Instead of providing meals for the subjects, they were instructed on food choices and told to prepare their own meals, making this a more realistic study. The greatest strength of this paper, published in the Journal of the American Medical Association, was that the people were followed for 18 months, which is really great, since many dieters tend to regain weight after the first year of weight loss. Thus, it is likely that the results found from this study would better represent long-term benefits from the two diets. Among the many subjects, most (75 percent) had normal insulin release, which was measured by testing blood insulin levels 30 minutes after drinking a sugary drink containing 75 grams of glucose. However, 25 percent released more insulin than their normal counterparts.
The total group of all subjects lost approximately the same amount of weight, regardless of the type of diet consumed. Thus, it appeared on the face of things that the low-fat and low-glycemic-load diets were equivalent. However, when the data among the high-insulin releasers were analyzed separately, it became clear that one of the diets was superior for producing fat loss and possibly improving cardiovascular health. Among this 25 percent, containing the high-insulin releasers, the low-glycemic-load diet resulted in a greater loss of body fat (nearly triple).14 The lipid profile, a measure of cardiovascular risk, was better among the subjects on the low-glycemic-load diet as well, with higher “good” cholesterol (HDL) and lower triglycerides (blood fats).
The value of this study and the findings are very important to the general public, as overweight and obese people make the great majority of the adult population and many are insulin resistant. However, for athletes who typically maintain a lower body fat and generally have a healthy insulin sensitivity profile, the value of the findings is less certain. The subjects in this study were obese and as noted, many had an elevated insulin response. Insulin resistance is commonly associated with the “apple” morphology, a shape not often seen in the competitive arena. However, as athletes and bodybuilders seek every advantage to maximize the positive results of their training and diet, it would appear that utilizing a low-glycemic diet during periods when fat reduction is the primary goal would be beneficial. Certainly, most athletes benefit from taking in a high-glycemic drink immediately after the workout. However, substituting those late-night Good & Plenty candies for an apple or yogurt may help keep the abs sharp and abdominal fat down.
Interesting trivia: Good & Plenty, produced by Hershey Foods, is the oldest branded candy in the United States, first produced by the Quaker City Confectionary Company in 1893. The scent of Good & Plenty candies is reported to increase sexual arousal in women.15
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