The Flat Belly Diet was created by Cynthia Sass, the nutritional director from Prevention magazine. The complete eating program helps dieters lose weight around their bellies by focusing on foods that are easy to digest and low in calories. However, certain foods and drinks, like coffee, are prohibited or limited on the Flat Belly Diet.

The Flat Belly Diet book has instructions on the four-day Jumpstart program, recipes, meal plans and optional exercises. A pocket guide to the diet is also available. Flat Belly Diet daily meal plans contain 1,200 to 1,600 calories, including breakfast, lunch, dinner and a snack. Every meal or snack has about 300 to 400 calories.

Fruits and vegetables provide fiber and nutrients. All vegetables should be lightly cooked. Fish, turkey and chicken are sources of lean protein, and red meat and higher fat meats are kept to a minimum. Smaller quantities of whole-grain carbohydrates are also part of the diet. Dieters replace saturated fat with foods high in monounsaturated fats. Olive oil, canola oil, olives, flax seeds, almonds and avocados are all natural sources of this fat, which is believed to reduce belly fat.

Dieters should avoid certain foods or beverages while on this diet. Caffeinated and carbonated beverages, like coffee, soda and tea, can cause stomach bloating. These beverages are completely prohibited during the four-day Jumpstart program but are allowed in moderation for the rest of the diet. Other prohibited or limited foods are chewing gum, sugar alcohols, excess salt, excess carbohydrates, raw/bulky foods, fried foods and overly hot and spicy foods.

Many people are dependent on coffee and experience headaches if they quit immediately. Dieters can have one cup of caffeine a day to prevent headaches during the Jumpstart program. However, dieters should include these calories in their daily calorie count. Some dieters include coffee in their Flat Belly Diet plan. However, they may opt for decaf coffee or reduce the number of cups they drink each day.

As an alternative to coffee and other caffeinated drinks, dieters are encouraged to drink Sassy water throughout the course of the diet. This low-calorie drink is made with cucumber, ginger, lemons and chilled water. Sassy water is a requirement for the four-day Jumpstart program. Another alternative to coffee is herbal teas, which contain no caffeine. Black and green teas are another option. Although teas do contain caffeine, it is still less than most standard drip coffee or espresso drinks.