Over the past few years “negative calorie” and “fat-burning” foods have become hot topics. Several popular weight loss plans are based on consuming these supposedly high-power diet foods. In general, they’re planting foods (in particular vegetables) that are very excessive in fiber and water content material however low in calories. But, according to some, very lean meats/proteins can also fall into the fat-burning food category.
The big question is: can they really help you lose weight in a faster, safer, and/or easier way?
The basic theory behind negative calorie foods is that they contain fewer calories than the human body needs to digest. So, the thinking goes, if you eat them in large amounts you’ll be able to more easily burn calories, even with a full stomach and very little hunger. If you eat only negative calorie foods — at least according to the theory — you’ll create a big net calorie deficit and be able to lose weight quickly without any other effort (like exercising).
Depending on which book or magazine article you’re reading, negative calorie foods also contain large amounts of special (magical?) plant enzymes which directly affect metabolism and/or the storage of body fat. The problem is that there is very little scientific evidence to back up any of these claims!
The basic theory behind “fat-burning foods” is that, in one way or another, they boost your metabolism so that you burn more calories more store body fat. Some of the most popular diets — including Atkins and the South Beach Diet — are based around foods that fall into this category.
It’s important to understand that ALL foods burn calories to some degree. Typically, your body uses between 10 and 15 percent of the calories in a piece of food during the digestion process. Some foods are harder to digest and, therefore, require more energy/calories to process. Also, different kinds of foods and ingredients have very different effects on the type and quantity of hormones the body produces after eating them.
Both the net calorie impact (the difference between calorie intake and calorie expenditure) and the net hormonal impact can vary widely between different types of food. A piece of celery and a piece of candy of the same size are going to have very different overall effects on your body after being consumed.
But even a piece of celery contains more calories than are required to digest it… and any positive “hormonal effect” it provides will be very, very small.
Also, diets based around eating nothing but low-calorie vegetables and very small amounts of lean meats — such as the famous “Negative Calorie Diet” — are incredibly difficult to stick to. They also often exclude one of the most important components of any healthy weight loss diet: good fats!
So no, there are no true negative calories foods or effective diets based around them.
That being said, it’s definitely a good idea to fill yourself up with high-fiber, low-calorie, and/or protein-rich foods when trying to lose weight. But it’s important to remember to eat plenty of healthy fats/oils and also to allow yourself a “cheat day” every once in a while. A good paleo-style diet fits the bill well and contains many of the so-called “negative calorie” and “fat-burning” foods.
Below is a shortlist of the foods often included in the “negative calorie” category:
Vegetables: Broccoli, Cabbage, Cauliflower, Asparagus, Celery, Endive, Green Beans, Cucumber, Onion, Papaya, Radishes, Spinach, Zucchini
Fruits: Apple, Cantaloupe, Cranberry, Blueberry, Grape Fruit, Lemon, Lime, Orange, Pineapple, Strawberry, Honey Dew Melon, Watermelon
Below are some of the foods often included in the “fat-burning” category:
Breakfast foods: Low-Fat Milk, Oatmeal, and 100% Whole-Grain Cereals. Calcium-rich and full of both soluble and insoluble fiber (great for keeping insulin levels in check and helping to prevent fat storage).
Spicy Foods: Many experts consider chili (or “chile”) peppers to be among the strongest of fat-burning foods. Cayenne, jalapeño, habañeros, Thai chilis, and other peppers all contain chemicals that can slightly boost the metabolism. Studies have even shown that eating a very spice meal can speed up the metabolism significantly for up to 3 hours afterward.
Beverages: Black Tea, Green Tea, Coffee, and Yerba Mate. These drinks all contain at least one form of caffeine, which is known to raise the metabolism and also help to “free” stored fats into the bloodstream (making them easier to burn off during exercise).
The teas — green tea especially — also contains a very interesting compound called epigallocatechin gallate, or “EGCG.” It has been shown to help exercisers burn significantly more calories and may even be able to boost the metabolism in non-exercisers.
Meats: Lean Beef, Chicken, Turkey, Pork, Buffalo, etc. All low-fat-content meats can help to speed up the metabolism simply because they require quite a bit of energy (calories) to digest and process inside the body. Studies have shown that people who eat a high-protein, meat-based diet burn up to twice as many calories after meals compared to people who eat a high-carbohydrate diet.
Fish/Seafood: Tuna, Salmon, Sardines, and most other oily fish contain large amounts of omega-3 fats, one of the most important of the “good” fats and a powerful natural metabolism booster. Studies have shown that omega 3-rich diets alter levels of leptin, a powerful hormone that determines whether your body burns calories for energy or stores them as fat. Less leptin in the blood means more calories burned, and omega 3-rich diets have been shown to help lower leptin production.