Dieting is the practice of eating food in a regulated fashion to achieve or maintain a controlled weight.
In most cases dieting is used in combination with physical exercise to lose weight in those who areoverweight or obese. Some athletes, however, follow a diet to gain weight (usually in the form of muscle). Diets can also be used to maintain a stable body weight.
Diets to promote weight loss are generally divided into four categories: low-fat, low-carbohydrate, low-calorie, and very low calorie.
Types of Diets
Low-fat diets involve the reduction of the percentage of fat in one’s diet. Calorie consumption is reduced because less fat is consumed. Diets of this type include NCEP Step I and II. A meta-analysis of 16 trials of 2–12 months’ duration found that low-fat diets (without intentional restriction of caloric intake) resulted in average weight loss of 3.2 kg (7.1 lb) over habitual eating.
Low carbohydrate diets such as Atkins and Protein Power are relatively high in protein. Low-carbohydrate diets are sometimes ketogenic (i.e. they restrict carbohydrate intake sufficiently to cause ketosis).
Low-calorie diets usually produce an energy deficit of 500–1,000 calories per day, which can result in a 0.5 kilogram (1.1 lb) to 1 kilogram (2.2 lb) weight loss per week. Amongst some of the most commonly used low-calorie diets include DASH diet, Diet to Go, and Weight Watchers. The National Institutes of Health reviewed 34 randomized controlled trials to determine the effectiveness of low-calorie diets. They found that these diets lowered total body mass by 8% in the short term, over 3–12 months.
Very low-calorie diets
Very low calorie diets provide 200–800 calories per day, maintaining protein intake but limiting calories from both fat and carbohydrates. They subject the body to starvation and produce an average weekly weight loss of 1.5–2.5 kilograms (3.3–5.5 lb). “2-4-6-8″, a popular diet of this variety, follows a four-day cycle in which only 200 calories are consumed the first day, 400 the second day, 600 the third day, 800 the fourth day, and then the cycle repeats. These diets are not recommended for general use as they are associated with adverse side effects such as loss of lean muscle mass, increased risks of gout, and electrolyte imbalances. People attempting these diets must be monitored closely by a physician to prevent complications.
Detox diets claim to eliminate undesirable “toxins” from the human body rather than claiming to cause weight loss. The general idea suggests that most food is contaminated by various ingredients deemed unnecessary for human life, such as flavor enhancers, food colorings, and artificial preservatives. Scientists, dietitians, and doctors, while generally judging ‘detox diets’ harmless (unless nutritional deficiency results), often dispute the value and need of ‘detox diets‘ due to lack of supporting factual evidence or coherent rationale. Detox diets can involve consuming extremely limited foods (only water or juice, a form of fasting), or eliminating certain foods from the diet (such as fats). Proponents claim that this will cause the body to burn accumulated stored fats, releasing fat-stored “toxins” into the blood, which can then be eliminated through the blood, skin, urine, feces and breath.
G.I. stands for Glycemic Index, a medical term used to measure the speed at which carbohydrates break down in the digestive system to form glucose. Glucose is the body’s source of energy – it is the fuel that feeds your brain, muscles, and other organs. Glucose is set at 100, and all foods are indexed against that number. So foods that are quickly digested have a high G.I., and foods that are digested more slowly have a lower G.I. The Low-Glycemic Index Diet was developed by Dr. David J. Jenkins, a professor of nutrition at the University of Toronto and later turned into a successful line of diet books by author and former president of the Heart and Stroke Foundation of Ontario, Rick Gallop.
Proper Diet and Nutrition
Food provides nutrients from six broad classes: proteins, fats, carbohydrates, vitamins, dietary minerals, and water. Carbohydrates are metabolized to provide energy. Proteins provide amino acids, which are required for cell construction, especially for the construction of muscle cells. Essential fatty acids are required for brain and cell membrane construction. Vitamins and trace minerals helps to keep good electrolyte balance and are used for metabolic processes. Dietary fiber also affects one’s health, although it’s not digested into the body.
Sometimes dieters will ingest excessive amounts of vitamin and mineral supplements. While this is usually harmless, some nutrients are dangerous. Men (and women who don’t menstruate) need to be wary of iron poisoning. Retinol (oil-soluble vitamin A) is toxic in large doses. Vitamin E supplements have been found in some studies to increase mortality, congenital heart defects in offspring and an increased risk of stroke (see the corresponding article). Most people can obtain their nutritional needs from their diet. In any event, a multivitamin taken once a day will suffice for the majority of the population.
Weight loss diets that manipulate the proportion of macronutrients (low-fat, low-carbohydrate, low-fat, low-GI etc.) have not been shown to be any more effective than diets that maintain a typical mix of foods with smaller portions and perhaps some substitutions (e.g. low-fat milk, or less salad dressing). Extreme diets may, in some cases, lead to malnutrition.
Besides the importance of eating a balanced diet that includes all the necessary nutrients, other factors also contribute to healthy nutrition. Eating 5 or 6 small to medium sized meals throughout the day (instead of three big meals) has been shown to improve the metabolism. As well, drinking sufficient amounts of water can help eliminate toxins and fat. Heavily processed and fried foods as well as sweets, junk foods, and alcohol should also be avoided in a healthy diet.
Also a topic of great importance discussed among nutritionists as well as psychologists is the attitude to weight-loss and the consumption of food in general. Voicing ideas such as “its just one burger” during and after weight loss regimes is discouraged, and often is said on the part of an insecure individual that has reached the unfortunate conclusion, that nothing can be done any longer and that any effort to do so is futile. The advice given is, avoid reaching such a conclusion, as not only does it change ones perception of the effect of excessive amounts of food on the body but also encourages, a ‘lack-lustre’ lifestyle, and approach to life as a whole.
Nutritionists also agree on the importance of avoiding fats, especially saturated fats, to reduce weight and to be healthier. They also agree on the importance of reducing salt intake because commercial foods such as snacks, biscuits, and bread, among others, already contain salt, thus contributing to an excess of salt daily intake.
For more info on Supplemental Nutrition Assistance Program: USDA Food & Nutrition Service
This web page is for information and support only and NOT a substitute for professional diagnosis and treatment! Nothing on this web page should be construed as medical advice. Please check with your own physician about any information that concerns you.