Very-Low Calorie Diets
Diets very low in calories (800 calories per day or fewer), including those that have been promoted as having a "protein-sparing effect" (conserving lean tissue), have often been associated with serious medical complications, including cardiac dysrhythmias (irregular heart rate that is sometimes intractable) and sudden death. Diets very low in calories Produce distinctive and abnormal electrocardiographic (ECG) rhythm patterns that are most likely a used by protein loss from the myocardium (heart muscle) or cell-membrane instability from rapid Weight loss.Stringent dieting is also considered a major trigger for binge eating. A 6-month experiment of healthy men who were put on a diet that provided about one half of their usual daily caloric intake resulted in massive eating binges in which the men ate up to five meals and 5000 calories a day until they had returned to their normal weight. Another problem with very-law-calorie diets is that they cause an adaptive response that decreases energy expenditure and increases fat storage. Repeated dieting may lower BMR on a long-term basis.
Low-Calorie DietsLow-calorie diets (800 to 1000 calories per day) result in atrophy of the heart muscle. When lowÂcalorie diets are accompanied by regular exercise, the muscle loss is minimized, but it still occurs. However, regular exercise combined with a moderate-calorie diet results in loss of body weight and gain of cardiac muscle. Exercise-induced cardiac hypertrophy results in a stronger, more efficient heart.
Low-Fat DietsLow-fat diets are potentially effective techniques for losing weight. With its high-caloric yield, low thermic effect, and almost unlimited capacity for storage, fat is a major threat to weight maintenance. Consequently the current fixation is on "fat-free" or "low-fat" foods. The assumption is that if a food is low in fat, it is also low in calories. Only 7% of Americans are concerned about calories, compared with 60% who cite fat as public enemy number 1.27 As a result, although Americans are consuming less fat calories percentage-wise, they are consuming more total calories from all sources and are getting heavier. (Actual fat intake remains the same as it was during the past 10 years. Percentage-wise, it dropped from 36% to 34% because of an increase in total calories consumed. ) Low-fat diets have not been effective for many dieters because the dieters have become volume eaters. Researchers at Pennsylvania State University demonstrated this point when on separate days they gave women one of three types of yogurt: low fat, low calorie; low fat, high calorie; and high fat, high calorie. The low-fat, high-calorie and high-fat, highÂcalorie yogurts contained the same number of total calories. Half of these yogurts were labeled either low fat or high fat; the other half were unmarked. Thirty minutes after consuming the yogurt, the women ate lunch. The women who ate the yogurt labeled low fat compensated by taking in more calories during lunch even if they ate the low-fat, highÂcalorie version. The women who ate the unlabeled yogurt, on the other hand, ate fewer calories at lunch after eating the high-calorie version. The researchers concluded that when the women ate yogurt labeled low fat, they rationalized that they could indulge more at lunch. But when they were given unlabeled yogurt, they were more tuned in to their bodies' physical cues and naturally adjusted the amount they ate. The attitude that people can eat what they want, in unlimited quantities, as long as it's fat free is wrong. Calories do count. Fat-free foods can help people lose weight if they are used properly, if they don't result in over compensatory consumption of food, and if total calories are kept in line.
Popular DietsMany diets on the market are nutritionally sound, and many are not. Some are potentially hazardous, and many are based on faulty nutritional and physiological concepts. Some require that food be eaten in a certain order and severely restrict allowable foods. Diets such as Jenny Craig come in pre measured servings. Some require medical supervision. Others impose unrealistic demands on caloric restrictions, and still others make promises based more on fantasy than facts. The Food and Drug Administration (FDA) does not investigate every new fad diet, and many diet plans are published without the FDA's endorsement. If a diet is published, it is usually because a publisher sees potential profits from its sales. Publishers know that the advice to "eat less fat and increase physical activity" will not sell books but fad diets with secret ingredients or magic formulas will. Because fad diets are unlikely to disappear, identifying some of the characteristics and marketing strategies used by diet promoters to appeal to unwitting consumers is helpful:
- They promote quick results.
- They stress eating one type of food to the exclusion of others.
- They emphasize gimmick approaches, such as eating food in a particular order.
- They cite anecdotes and testimonials, usually involving well-known people.
- They claim to be a panacea for everyone. They often promote a secret ingredient.
- They often recommend expensive supplements.
- They rarely emphasize permanent changes in eating habits.
- They usually show little concern for accepted principles of good nutrition . They are usually cynical of the evidence that comes from the scientific community.
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