Low calorie diets are based naturally on low calorie intake. The mechanism functions on the principle that the body will burn fat if the necessary energy is not provided by food. To establish precisely the necessary limit for the normal functioning of the body is very relative and depends on individual needs. Metabolism is not the same for all people. It varies according to age, gender, physical state and type of activity. Besides, it may adjust to the amount of food provided. When food is provided in lower quantities the metabolism will slow and burn a lower number of calories.

It has been established that, in average, men need around 2,200 calories a day while the daily requirement for women is around 1,800 calories a day. Low-calorie diets restrict the calorie intake to around 1,000 calories a day. There are also very low-calorie diets that recommend 800 calories a day or even less. These diets permit slight adjustment for special needs, for example when a person is exercising regularly or leading a very active life, or when you do not need to get rid of too much weight in a very short time. For example, take into account the fact that one pound is the equivalent of 3,500 calories. You can shed one pound in a week by cutting out 500 calories daily.

Diets of this kind are certainly not recommended for old people, for pregnant or breastfeeding women, or for children and adolescents.

Permitted Foods

For low-calorie diets there is no specific list of permitted foods. The only characteristic must be a low-calorie content, or a balance so as the total number of calories stays within the daily permitted number. The diet must contain all essential nutritive elements, to maintain good health.

Diet Plan

A personalized diet plan should be built, combining the foods you like and may constitute acceptable low-calorie meals. It is advisable that a daily (or better weekly) plan is conceived before starting the diet, so that cheats are avoided out of lack of meal ideas.

There are some things to pay attention to: foods' energy value, food composition (fats, carbohydrates and proteins - avoid high-fat and high-carbohydrate foods), avoiding adding high-calorie ingredients during cooking (e.g. fats and oils), maintaining adequate water intake, limiting alcohol consumption, reducing portion sizes.

1000 Calorie Diet Sample

• Lean meat/protein: Seventy grams of tuna (canned in brine), 70g roast chicken breast
• Bread/starch: Two small slices of wholemeal bread, one wholemeal roll, 80g potatoes, one cereal bar
• Fruit: One small banana, 200 ml orange juice
• Vegetables:Fifty grams lettuce, 50g sweet peppers, 10g spring onions, 60g broccoli(steamed), 50g carrots(boiled)
• Dairy(low fat): One hundred grams fruit yoghurt, 200 ml skimmed milk
• Fat: Ten grams reduced calorie mayonnaise

1200 Calorie Diet Sample

• Lean meat/protein: One poached egg, half a cup drained water-packed tuna, 50g lean chicken breast
• Bread/starch: Three-quarters of a cup (6 ounces) bran flakes, one slice bread, half a cup cooked pasta, three graham crackers
• Fruit: One small banana, one medium orange, one and a quarter cups melon cubes
• Vegetables: Half a cup of chopped celery, two tomato slices, one lettuce leaf, one cup steamed broccoli
• Dairy(low fat): Two cups skimmed milk
• Fat: Two teaspoons low-fat mayonnaise, one tsp margarine
• Drink: One can diet soda

1500 Calorie Sample Diet

• Lean meat/protein: Fifty grams sliced turkey breast, 80g lean roast beef
• Bread/starch: three quarters of a cup corn flakes, one slice toast, two slices bread, one baked potato, one medium dinner roll, four graham crackers
• Fruit: One small banana, 1-1/4 cups fresh strawberries
• Vegetables: One lettuce leaf and 2 tomato slices, 1 cup carrot sticks, 1 cup cooked mixed vegetables
• Dairy(low fat): Two cups milk (1% fat), 1/4 cup low-fat cottage cheese
• Fat: Two teaspoons margarine, 1 tsp. regular mayonnaise, 2 tbs. salad dressing

Advantages and Disadvantages

Advantages

When used moderately, without trying to restrict a great amount of calories at once, low-calorie diets are among the healthiest ways of losing weight. You have the choice of a great variety of foods, permitting the intake of essential nutrients.

Disadvantages

Diets of this kind can lead to temporary weakness. If used to rapidly lose a great deal of weight, they might have short-term results and be followed by rapid weight regain. They are not easy to follow. Permanently watching and counting calories can become frustrating.

Conclusion

Moderate calorie restraint will not have a negative effect on health as long as the right nutrients are present to maintain minimum health. But you may starve!

Negative Calorie Diet

There is a theory according to which some foods would require more energy burn for the body to process their components(vitamins and minerals). In the final result, instead of burning the calories contained in that particular food, our body will actually burn an additional 50% of the calories ontained. That is, the total amount of burnt calories would be 150%.

Such negative calorie foods would include: Asparagus, beet, broccoli, carrots, cauliflower, celery, chili peppers, cucumber, dandelion, endive, garden cress, garlic, green beans, lettuce, onion, papaya, radishes, spinach, turnip, zucchini.

This theory has no scientific basis.