Balance is the key to the Zone Diet. According to it creator, Dr. Barry Sears, eating an ideal ratio of carbohydrates to protein to fats is the key to weight loss. On the Zone Diet, dieters consume 40 percent of their calories from carbohydrates, 30 percent from protein and 30 percent from fats. Dieters eat five times a day, preferably before they get hungry, and low-fat protein sources are recommended. Meals should not exceed 500 calories and snacks should contain approximately 100 calories.
Weight Watchers helps dieters lose weight by providing guidance, education and group support. At the heart of the plan is a points system. Weight Watchers has compiled an extensive database of foods, even prepackaged and restaurant foods, and has assigned a point value to each one. Each dieter is allotted a specific number of points each day, based on weight loss goals and individual lifestyle. Weekly meetings, with weigh-ins, provide a sense of community and support.
The Atkins Diet claims that the excess consumption of carbohydrates leads to weight gain and obesity. During the first two weeks, dieters must limit carbohydrate consumption to less than 20 g per day. High-protein foods such as meat and eggs replace carbohydrates in the diet. After the two-week induction phase, dieters may reintroduce natural carbohydrates from vegetables into their diet. However, sweet fruits and grains continue to be severely limited. According to Northwestern University, people on the Atkins Diet are at risk for vitamin deficiencies and increased levels of the bad LDL cholesterol and constipation.