We are on a constant search for ways to lose weight on both sides of the equation, meaning we are always looking for ways to decrease calorie intake (and still be able to eat Christmas cookies) and we are always searching for ways to burn more calories.
We really like the idea of burning more calories without working for it. Really, isn’t that the magic pill people are looking for?
The thermic effect of food is one of those exercise-free mechanisms to burn more calories. The “thermic effect” refers to an increase of metabolic rate after eating food. It costs energy to eat and digest food. Our basal metabolic rate is when we are sitting around doing nothing. As soon as we start doing something, tapping a finger, or even digesting a cookie we are burning calories. We’ll skip the benefits of chewing every bite an extra 20 times as we don’t want to become a country of round-headed, muscle-faced, pit bull-looking over-chewers. Instead, we’ll focus on the heat produced by digesting and storing food.
Chilies, not celery
Some foods are easier to process than others. Studies show that 20% to 35% of protein calories consumed is used up during the digestive process. Whereas fats and carbohydrates range from 5% to 15% of energy consumed. The joke that celery burns more calories than you eat because of the work needed to digest it has not been verified. A study did show that adding chilies to a diet increases the thermic effect, which technically means that eating hot peppers helps you lose weight.
The mechanism of the thermic effect of food are not fully understood. It is hypothesized that vegans who eat a low-fat diet have increased the thermic effect of the food they eat. This might be due to depleting fats within liver and muscle cells. This lack of fat is believed to increase mitochondrial energy (remember the powerhouse of the cell?) and an increase in metabolism after eating.
A recent four-month study of 244 overweight to obese people measured these effects. One half of the participants were put on a low-fat vegan diet and the other half just kept eating their normal diet. Obviously, this was a major change for many of the participants. The weight lost wasn’t just due to a change of thermic effect — many people were now eating a diet much higher in fiber, lower in fat, and lower in energy density.
The study group was put on a diet of 75% carbohydrates, 15% protein, and 10% fat. The group receive classes and cooking demos as well as printed materials on what foods to eat and what meals to make. The researchers didn’t provide any meals and trusted the participants to make their own food, not break the rules and accurately report what they ate. This degree of freedom was a real weakness in the study, but at the same time, replicates real life. After all, if this article stimulates anyone to change their diet, rest assured I won’t be looking over their shoulder to “tsk tsk” when they break the rules.
Less booze, same exercise
Both groups were asked to limit alcohol and make no change to their exercise habits. Then, over the next four months a bunch of tests were taken.
The newly vegan group lost an average of about 14 pounds each. The control group lost about 1 pound each. This implies just knowing someone is looking over your shoulder at what you eat isn’t a real motivator to change a diet. Cholesterol and LDL levels decreased significantly. So did insulin resistance. This is important for diabetics and those with pre-diabetes.
Forty-four subjects underwent imaging to examine liver fat levels. Pate lovers know that fatty livers taste better, but they definitely aren’t healthier. The study group has their liver fat levels drop by just over one-third. The decrease in liver fat level is believed to increase the thermic effect of food. It was also directly related to decreased insulin resistance. This study was one of the first to show that direct relationship.
Although hard to prove, the study did show that switching to a vegan diet for only four months had a significant effect on insulin resistance and weight loss.
Just maybe, this New Year’s resolution should include becoming vegan. It isn’t easy. Some start with a day a week, then two, and keep moving up as they learn what meals they like. Others quit cold turkey (literally and figuratively) — now that we’re past Thanksgiving it should be easier.
Dr. Salvatore Iaquinta is a head and neck surgeon at Kaiser Permanente San Rafael and the author of “The Year They Tried To Kill Me.” He takes you on the Highway to Health every fourth Monday.