The pineapple and tuna diet is a three-day fad diet intended to produce rapid weight loss. As you learn more about the diet you'll clearly see how and why this diet is an unhealthy fad and shouldn't be attempted. According to "Diets Exposed: Analysis of Popular Fad Diets," if a diet claims that you can lose more than 2 lbs. per week, limits your intake to only a few foods or cuts an entire food group out of your diet it is likely a fad diet.
The pineapple and tuna diet lasts three days and promises a 5 lb. weight loss. The diet requires that you eat only the foods on the menu in the amounts specified. Eat six small meals per day. Water is the only permitted beverage on the diet. Intense exercise is discouraged during the diet. If you wish to exercise, try stretching or yoga.
On the first and third days of the diet you eat six meals consisting of 1/4 of a pineapple or approximately 1 cup of pineapple chunks. Space your meals two to three hours apart. Eat 1/4 of a pineapple for your first, third, fourth and sixth meals of the day. For your second and fifth meals of the day, eat 6 oz. of fresh tuna or canned tuna packed in water.
Because the diet provides only approximately 500 calories per day, rapid weight loss is likely to occur. However, very little of the weight you lose is likely to be fat; most of it will be water and muscle. Because muscle burns more calories at rest than fat, losing muscle mass has a profound negative impact on your metabolic rate and increases your chances of experiencing rebound weight gain after the diet.
Diets providing 800 calories per day or less, like the pineapple and tuna diet, are classified as very low calorie diets. Due to your metabolism slowing on a VLCD, these diets should only be performed under the supervision of a physician, according to "Handbook of Obesity Treatment," and should be used only when rapid weight loss is absolutely necessary for your health. Lasting weight loss requires you to form a balanced diet and exercise regimen you can stick to forever.