Center for Human Nutrition

Medical Nutrition Syllabus

Guide to Healthy Diet and Lifestyle

Exercise Guidelines

Managing Obesity

Exercise Prescription

Medicine and Surgery Nutrition Assessment Checklist

Pediatric Nutrition Assessment Checklist

Adolescent Nutrition Assessment Checklist
Syllabus Menu: | Dietary Assessment | Weight Assessment | Dietary Recommendations | Nutritional Deficiencies | Nutrition During Lifecyle | Nutrition in Pathological Conditions | Vegetarianism | Popular Diets | References |

Popular Diets

Many popular diets offer the false promise of very quick weight loss. Unfortunately, many of these diets are not only unsuccessful but are often nutritionally inadequate. The only way to achieve permanent weight loss is to change eating patterns for a lifetime. An adequate weight-loss diet should be restricted in calories, but an unsupervised diet generally should not fall below 1500 calories per day for men and 1200 calories per day for women. A diet with fewer calories than these minimal amounts may not be able to meet basic nutritional needs. It should include foods from all the food groups and should reduce energy intake by cutting fats, sugars, and large portions.

Common problems with popular diets

  • Too high in any one nutrient - Too much fiber may reduce intake of other nutrients.
  • Too little of any one nutrient - A dairy-free diet may be low in protein or calcium, especially for women.
  • Restricting liquids - May lead to dehydration and false weight loss through fluid loss.
  • Unrealistic weight loss promises - Loss should average 1 to 2 pounds per week for most individuals. Some obese individuals may experience more weight loss.
  • Too expensive - Many programs rely on foods difficult to obtain or too expensive.
  • Little variety, boring - Eating patterns should include a variety of foods from all the groups.

Examples of specific diets

  • High-protein, low carbohydrate diets - An example of this diet is the Zone Diet. It consists of consuming quantities of protein in unrestricted amounts, including meat, fish, shellfish, poultry, eggs, and cheese. Pasta, bread, and foods with large amounts of refined sugar are eliminated. This diet is popular because pounds drop off very quickly in the beginning, mostly due to water loss, and meat lovers get to indulge endlessly. Some research suggests that high-protein foods, such as meat and cheese, may slow the rate of absorption of carbohydrates, so that blood sugar levels remain steady and keep hunger at bay. The problems with these diets is that they may produce kidney problems, ketosis, and uric acid stones, and may cause the dieter to feel fatigued due to low-carbohydrate intake. Also, protein-rich diets tend to be full of saturated fat and cholesterol, which can increase the risk of heart disease.
  • Food Combination Diets - Examples of this type of diet include the Beverly Hills Diet by nutrition guru Judy Mazel, and the Fit for Life Plan. These diets are based on the assumption that fruit enzymes could burn up calories before they hit your hips, and advocate eating carbohydrates and proteins at different times. The Beverly Hills dietís first ten days calls for eating nothing but fruits. Portions are generous -- a half pound of prunes at a single meal, five pounds of grapes in one day. On Day 11, a half pound of bread, two tablespoons of butter, and three ears of corn are added; only on Day 19 is a complete protein (steak or lobster) included. Dieters can indulge in fatty treats, like cheesecake and ice cream. People like this diet because weight loss comes early, since fruits are very low in calories. Dieters who thrive on discipline find the Beverly Hills structured plan appealing and some enjoy the sweet allowances. The problem with this diet is that there is no scientific evidence that the body processes particular combinations of foods any differently than random ones. The Journal of the American Medical Association deemed it "the worst entry in the diet-fad derby"). It stated that it may cause diarrhea, and because it's low in protein, it promotes breakdown of muscles and vital-organ tissue.
  • Liquid Diets - These diets call for the dieter to drink a shake in place of two meals and one snack. SlimFast and Nestlé Sweet Success are examples of this diet. The third meal should be a low-fat combination of nutrient-rich foods amounting to 600 calories. Each drink weighs in at about 200 calories and one-to-three grams of fat. Liquid diets are popular because they are very convenient and many of the shakes actually taste good. Also, many of these shakes are nutritionally balanced. However, if the dieter reverts to old eating habits after stopping the meal replacements, the pounds will probably return.

Commercial Weight-Loss Programs

  • Programs such as Jenny Craig, Nutrisystem, and Richard Simmons Slimmons combine diet, exercise and behavior modification. They require the purchase of special foods in order to participate in the program. The cost of these foods can add up over time.
  • Diet Workshop, The Solution and Weight Watchers offer similar programs, with more emphasis on lifestyle counseling and group support. There is a fee for their services.
  • Overeaters Anonymous (OA) and TOPS (Take Off Pounds Sensibly) charge no fees and consist of support groups that help participants achieve and maintain weight loss. OA uses the 12-Step Program similar to Alcoholics Anonymous.