Fad diets such as a meat and fruit diet are meant to encourage short-term weight loss, and they can be successful. However, there are potential risks to eating such a limited variety of foods, and there's no guarantee that you'll lose any weight as a result of following the plan.
Before you start to follow any new diet plan, it's important to understand that the number of calories you eat and burn is what determines weight loss, not the specific foods you choose. You must burn more calories than you consume over an extended time to successfully lose weight, and the only way a meat and fruit diet could accomplish that would be if it lowered your daily calorie totals.
The nutrition facts of the foods you eat on the diet make a difference. Filling up on low-calorie foods is more likely to lead to weight loss than choosing energy-dense foods that are high in calories and fat. According to the USDA, for example, a cup of watermelon pieces has only about 45 calories, but a large banana has about 135 calories. Even greater variation is present in meat products. A few slices of turkey deli meat have about 100 calories and 1 g fat, but a large sirloin steak has close to 1,000 calories and 65 g fat.
Because a meat and fruit diet excludes major food groups and disregards balanced eating, it's not sustainable in the long term, and you may put any weight you lose right back on when you quit following the diet. A safer and more reliable way to lose weight, according to the National Institutes of Health, is to follow a low-calorie diet that includes a balance of items from every major food group.
The amount of weight you can lose by eating just meat and fruit is dependent upon how many calories you consume. If you normally eat about 2,000 calories and the new diet brings you down to 1,500 daily, for example, you'll lose about a pound per week, or a total of two pounds. If you eat closer to just 1,000 calories per day, you could lose two pounds per week. The amount of physical activity you do also makes a difference; if you exercise more during the diet period, you may lose more weight.
Talk with your doctor or a registered dietitian before you make any big changes to your current eating plan. According to MayoClinic.com, the most successful weight loss diets tend to include foods that are nutritious and balanced, that you enjoy eating and that you will want to eat indefinitely, since weight loss and weight maintenance are lifelong processes. Eating just fruit and meat at the expense of other food groups has the risk of leading to nutrient deficiencies, fatigue or other health problems.