In fact no food has minus calories. A food may have very few calories but not without any calorie. So the name appears to be inappropriate. But there are reports of negative calorie effect in some food items.
Calorie is a unit of energy. The energy can be measured by many methods. The calories in foods depend on their composition and the calorie value of a food is not actually its measured values, but is the average energy of a large number of different samples of the food.
1 calorie = 4.184 joule
1 negative calorie = -4.184 joules
Commonly Calories refer to kilocalories.
1 kilocalorie (kcal) = 4.184 kilojoules (kJ)
Our body expends energy (calories) all the time, even if we are sleeping. We burn roughly 60 calories per hour while asleep and 85 while eating! Likewise we also expend calories while eating. Some foods need more calories and some less.
Foods use more calories to digest than the calories food actually contains are said to possess negative calories! Calories from these foods are much harder for the body to use. In other words, the body has to work hard in order to extract calories from these foods.
Even though a food may contain equal amount of calories, much less of these calories can possibly turn into fat in these foods as fewer calories are actually available to the body.
Consider the facts:
A piece of dessert consisting of 400 Calories (actually 400 kilocalories) may only require 150 Calorie (actually 150 kilocalories) to digest by our body, resulting in a net gain of 250 calories which is added to our body fat !
On the other hand, a 5 calorie raw piece of celery will require much more calories to chew and digest, so resulting in a net loss of calories from our body fat !!
Therefore, these foods are said to be good for achieving weight loss as they act like foods that burn fat.
Explanation of This Effect. How does it work?
Has this effect been scientifically explained or evaluated? To get answers to this question, we searched on the Internet and got the following supporting reports:
- All foods have a nutrient (carbohydrate, fat, protein), caloric (calories) and vitamin & mineral content. Vitamins stimulate living tissues to produce enzymes that breakdown the caloric nutrients of that food.
The foods with minus calorie contain sufficient vitamins & minerals that produce enzymes in quantities sufficient to break down not only its own calories, but additional calories from body in digestion as well. This is called "negative calorie effect".
This gives these foods a tremendous natural fat-burning advantage.
- If you look at the list of these foods given in the right column, you will find that these are natural plant foods like vegetables, fruits, beans, etc. having low fat, low calories, good amount of carbohydrates and dietary fibers. In the countries where the people who eat mainly these foods are found to be lean and thin.
Dr. Neal Barnard M.D, author of the Book "Negative calorie effect" has supported this concept. He says that the carbohydrate present needs much energy to breakdown these foods in the process of eating and digestion.
- Dr. Dean Ornish, M.D. of the University of California has reported the results of a diet consisting mostly of fruits and vegetables with no prescribed exercise program that he gave to his patients. He found a dramatic weight loss in his patients that could only be attributed to the consumption of these foods.
These foods will have maximum benefits when eaten without any empty calorie foods (junk food). Some of the foods that can be eaten in generous quantities are: Asparagus, Beets, Carrot, Zucchini, Papaya, Strawberry, Raspberry, etc. Look at the list given in right column.
Negative Calorie Diet
This diet is based on the fact that in order to lose weight you have to burn more calories than you consume. The diet recommends to eat the foods from the above list. The diet based on these food (some says it zero calorie diet) is very helpful in losing weight. This results in your body burning up the excessive stored fat!
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Although the above studies and reports do give some explanation directly or indirectly in support of the concept, yet a scientific thorough study is needed. Till that time, it can be said that eating these foods is a better alternative to fad diets. Since these foods are low in calories (100 g of celery, cabbage, cucumber or lettuce have about 14 calories each; asparagus has 20 calories, carrots 40 calories, broccoli 25 calories, etc.) and fat, one thing is certain - these are not going to increase your body fat. At least you can eat them to offset calories in other foods.
These can therefore form part of a perfectly balanced diet. You may include maximum number of foods from the above list in your daily diet without any adverse effect.
Conclusion: All foods have some calories. No food is actually "minus calorie food". BUT the overall effect of certain foods in our body is that of reducing calories consumed.