While I was busting the myth of stupid GM Diet , I came across a term called “Negative Calorie foods”. Now, being a research junkie, my ears started ringing to this fancy term, which sounded too attractive. I searched on Google, for the same, and surprisingly found a number of famous health websites, promoting this fad. Well, these famous websites, promote almost all other fads too, cause it’s difficult to find few sensible websites sighting research and good info on nutrition, fitness and health.
Acc. to a 2014 study in the Kuwait Medical Journal, by a team of Iranian & Ukranian researchers, led by Mohammadreza Rezaeipour, recently negative-calorie diet (NCD) has gained a great deal of research and popular attention. The origin of the NCD idea is still unclear. This notion first appeared in the website www.negativecaloriediet.com as an 80-page downloadable e-book in 2007. The negative calorie diet is a kind of very-low-fat diet (details of diet: 15% protein, 75% carbohydrate, 10% fat) that have a very high carbohydrate and fibre content.
University of Alabama researcher Katherine M. Buddemeyer & team, in a 2019 study titled “Negative calorie foods: An empirical examination of what is fact or fiction”, suggested that, in theory, these are foods for which more energy is expended in their digestion, assimilation, and nutrient storage than is gained. Therefore, their consumption results in a caloric deficit due to both the lack of net energy gained and that stored energy (i.e., fat) must therefore be utilized to fuel the completion of digestion and processing. Negative-calorie foods are generally characterized by a high fibre and water content and low caloric density. Topping the well-touted lists of negative-calorie foods are celery, lettuce, grapefruit, cucumber, and broccoli
For example, suggests Rezaeipour & team, that for digesting a piece of dessert containing 400 calories, the body needs 150 calories of energy. The remaining 250 calories add to the body fat. However, based on the idea of NCD, eating a 100-calorie dessert needs 150 calories for digestion. Actually, the body should burn 50 extra calories simply by eating the food. This idea for weight loss is appealing. This gives such foods, a natural fat-burning property. They are called catabolic foods. So, in simple terms, the NCD diet will help you in reducing overall calorie intake than help you in burning the excess calories.
SCIENCE BEHIND THE MYTH
Let’s understand the basics first:
TEE (total energy expenditure) – is the amount of energy (calories) spent on an average in typical day.
To calculate TEE, the formula is:
TEE = BMR (BASAL METABOLIC RATE) + TEF (THERMIC EFFECT OF FOOD) + ENERGY EXPENDED DURING PHYSICAL ACTIVITY (app. 20% of total TEE)
BMR or Basal Metabolic Rate is the energy required for core body functions and is measured at complete rest without food and it accounts for app. 60% of daily energy expenditure in a sedentary person.
Thermic Effect of Food (TEF), which accounts for around 10% of the daily energy needs. This is basically the effect which one gets from digestion and absorption of food.
Energy expenditure in the name of Activity Thermogenesis which is further divided into 2 types Exercise Activity Thermogenesis (EAT) and Non-Exercise Activity Thermogenesis (NEAT).
Our focus here is TEF, or the energy needed for digestion of foods. Different foods have different TEF, that’s why a different effect on the body when it comes to weight loss. For e.g. the TEF for fat is very low, as fats are assimilated very easily in the body. So, the body doesn’t spend much energy to digest fats. On the other hand, proteins take a lot of calories to digest, so is a recommended food during weight loss. Same is the case with high fibre foods.
For the study, fifteen healthy female volunteers consumed 100g of celery. DIT & RMR (Resting Metabolic Rate) was measured before and after the celery consumption in the subjects. It was found that the consumption of celery (16kcal) did not induce a negative energy balance in healthy women. However, the DIT of 100g of celery was 86% of the total energy intake. This fact combined with the high fibre and water content of celery does make it a good snack for inclusion in a diet for weight loss or management.
To determine the physical quantity of celery required to sustain a human for a day, the BMR of the subject must be known. This is calculated using the Harris-Benedict Formula, as specified for women:
[Men: BMR = (13.397 × weight in kg) + (4.799 × height in cm) – (5.677 × age in years) + 88.362
Women: BMR = (9.247 × weight in kg) + (3.098 × height in cm) – (4.330 × age in years) + 447.593]
Using the formula above, the BMR of the subject was estimated to be 1382.6707 kcal/day. Given that a 100g portion of celery contains app. 16kcal, the subject would need to consume app. 8.64kg of celery/day to meet their BMR requirements.
However, due to diet induced thermogenesis (DIT), 14% of the celery calories consumed are burnt in the process of consumption. This means that the subject would now be required to consume app. 10.05kg of celery per day, a number which in any case looks impractical.
Watson suggests that, the volume of food that a human would have to eat to meet the most basic calorific requirements (10.05kg) would not be physically possible to consume within a twenty-four-hour period. Along with this, if it were assumed that a ‘normal’ amount of food was consumed each day (except the only food consumed were celery) there would be a significant calorific deficit. This deficit would not be sustainable as a long-term diet without serious health repercussions.
Researchers found that, both experimental groups showed a similar pattern of weight loss. Weight loss obtained by NCD had no advantage over LCD as regards the lipid profile and preventing the occurrence or development of cardiovascular dysfunctions in sedentary overweight / obese middle-aged and older men.
Researchers found that, although, the celery meals were inherently low in energy, the lizards of this study did achieve a net gain of energy from this meal.
In short, ‘negative calorie foods’ is a myth. It is just an attractive phrase to grab attention of those looking to lose weight, and is heavily used for marketing.
Examine.com has compiled it perfectly when it says, “There is no evidence that a food can possess negative calories, thereby directly contributing to with weight loss. But foods typically categorized as ‘negative calorie’ items tend to be high in water and fibre, so their consumption may lead to weight loss because you consume less food overall”
Acc. to dietician Christy Wilson, a freelance writer for the Academy of Nutrition & Dietetics in US, “As enticing as it seems to eat foods that require more energy to chew, digest and absorb than they actually contain, there is no research to support this claim. Although foods such as celery, lettuce and cucumbers may have negligible calories, make no mistake, they still count towards a day’s worth of calories… these low-calorie, plant-based foods are an important part of a balanced diet, but, alone, lack adequate nutrients, including protein and fat, to sustain a healthy body.”
Every few years, every few months, there is new group or a set of population that needs to know how to make a start….this article focuses on that set of people, who wish to make a start. A fitness lifestyle, is a choice. Fitness, is a choice. It requires commitment, hard work and discipline. The […]
The Kashmir Files, by Vivek Agnihotri, took the country by storm, and created history when it became one of the highest grossing movies in Indian cinema, crossing well over 300cr in revenue, and continuing. The most amazing fact was that, the movie was made in a budget of just 15-20cr. What was even more surprising […]
When I made the biggest series on height , and the queries related to it. I also wrote an entire eBook(HEIGHT INCREASE – THE BITTER TRUTH/हाइट इनक्रीज़ – ए किलर ट्रुथ) on it , and tried to bust every possible myth related to it, based on proper evidence and research. I explained what factors may […]