Understanding the Thermogenic Effects of Food

It might come as quite a surprise to many health-conscious people that not all Calories are created equally. Depending on where you get your Calories from, you may actually be getting less Calories than you think.

The Thermogenic Effect as it pertains to food is a term used to refer to the way that the foods you eat can increase the amount of heat your body generates as it digests them, resulting in an increased metabolism for a short amount of time.

At its most basic level, the Thermogenic Effect is a result of your body having to consume energy in order to digest your food. Some sources of energy are less available than others, and thus require more effort to make use of in the body. It is important to note that this effect only applies on a macronutritional level--it will make either no difference or a ridiculously negligible difference if you try to make it harder for your body to digest foods by not chewing them as well. The rule still applies: liquify it. As you seek an increased metabolic rate, you'll likely end up with indigestion and bloating.

Protein is at the top of the hierarchy of macronutrients, as far as the Thermogenic Effect goes. A whopping 27% (on average) of the calories you consume from protein are used in the process of digesting the protein. Most of this is attributed to the fact that the protein has to be broken down into amino acids which then can be made use of, which is a labor-intensive process intracellularly. If you were to consume 300 Calories in pure protein (such as by a pure protein powder, or eggwhites, or something similar), the Thermogenic Effect would burn off 81 of those calories just during the act of digestion, leaving you with 219 calories.

Carbohydrates come in the middle of the hierarchy, or in second place, if you're the glass-half-full type. Calories consumed from carbohydrates experience a 7% (on average) Thermogenic Effect. This is quite a bit less than Calories from protein, but it's still one more strike against the "carbohydrates make you fat" theory. Part of the reason the Thermogenic Effect is so much lower for carbohydrates is that carbohydrates, in terms of human physiology, has been the food of choice longer than proteins. It tends to be more bioavailable, and depending on the glycemic index of the carbohydrate (whether the energy is released very quickly or very slowly), the Thermogenic Effect may be more or less than 7%. Low GI carbohydrates tend to have a slightly higher Thermogenic Effect because they are actively dispersing energy over a longer period of time. Yet another reason to avoid refined sugars--they're all very high up on the glycemic index.

Fats are in third place of the hierarchy, and I'm not saying last because I happen to place a large amount of value on fats. They have a pretty low Thermogenic Effect of 3%, on average, meaning that the Calories you think you're getting are, for the most part, the Calories you are getting. Fat is the most bioavailable macronutrient, hence the low amount of energy needed to make use of it. However, this does mean that it is a good idea to not eat many fats. Fats will help you stave off hunger longer, and during the early stages of human evolution, fat was rare and very nutritionally valuable. With 9 Calories per gram and only 3% of those Calories being consumed during digestion, it was an extremely portable, nutritionally dense treat. It is possible to survive on a very high-fat diet, and even mostly replacing all protein with fat, as the Inuit and Eskimo have done for thousands of years. While this is not advisible or even ideal, it is possible.

In addition to having to do with the macronutrient origins of your Calories, the Thermogenic Effect also has a lot to do with your actual eating pattern. If you eat only one meal a day and don't eat breakfast, you are greatly reducing your potential to see gains from the Thermogenic Effect (which, in this context, is nearly indistinguishable from simply increasing metabolism). Instead, it is advisible to eat several (6-8) smaller meals, spreading out your daily caloric intake throughout those meals, and spacing them as evenly apart as possible. Eating in this pattern consistently can further increase the metabolism via the Thermogenic Effect by an upwards of 10%.

This information is interesting, but do not let it pilot your inherent nutritional compass. If eating more protein is not working for you to lose weight, and you find you thrive on a higher fat diet, do that. No one can thrive on a low-carbohydrate diet, and very high carbohydrate diets accompanied by a lack of physical activity often result in apathy, depression, and generally feeling down.

Thank you for your time.