Less is More: Negative Calorie Foods

So we've all heard about negative calorie foods, right? If you make a quick google search, you'll find a list of fruits and vegetables that are considered "negative calorie" foods: apples, cranberries, grapefruit, lemon, mango, orange, pineapple, raspberries, strawberries, tangerines, asparagus, beets, broccoli, cabbage, carrots, cauliflower, celery, chile peppers, cucumber, dandelion, endive, garden cress, garlic, green beens, lettuce, onion, papaya, radishes, spinach, and turnips. The idea is that these types of foods have less calories than it takes to digest them; i.e. their thermic effect (the amount of energy expenditure above the resting metabolic rate and exercise) is greater than their caloric content. As we learned during our metabolism lecture in physiology, it is beneficial to eat small meals throughout the day because it takes quite a bit of energy to kick start our metabolism. So, it seems logical that if you eat a fruit or vegetable that contains zero or close to zero calories, this would expend more energy during digestion and result in negative calories.



I recently thought of writing a blog about this topic and started to do some research. As it turns out, there is almost no research out there discussing negative calorie foods. One article I came across discussed the "negative calorie illusion." People are under the impression that "negative" calorie foods cancel out other types of foods. In a study done by Chenev et al., participants rated a cheeseburger with celery as having less calories than a cheeseburger by itself. This study really highlights the flaws in the way our society thinks. If I eat a pound of celery, it doesn't mean that cancels out the quarter pound cheeseburger I also just ate.

Throughout a day, 5-10% our our energy expenditure accounts for digestion. As Dr. Hensrud of Mayo Clinic states, "it is theoretically possible to have a negative-calorie food, but there are no reputable scientific studies to prove that certain foods have this effect."So, it is likely that you could lose weight if you only ate negative calorie foods, but, as we learned in physiology, it is essential to couple a healthy diet (including carbohydrates, proteins, and fats) with healthy exercise in order to maintain a healthy weight and lifestyle. 


References: 
Forwood SE, Marteau TM. 2012. Are genetic association studies useful for the elusive negative calorie illusion. Replicating Chernev's calorie estimate findings. Appetite. 59(2):629.

http://caloriecount.about.com/forums/foods/list-negative-calorie-foods

http://www.mayoclinic.com/health/negative-calorie-foods/AN02040