Updated: Feb 22, 2019
Previously, we talked about Resting Metabolic Rate (RMR) and how it could impact your daily energy expenditure. Here, we will cover the eating part and it's influence on your energy output. This is the third strategy we use in our weight loss programme conducted by our personal coaches in Singapore.
Food is simply not calories you put in your body, but also the calories you get to burn when you ingest something. Thermic effect of food (TEF), also known as diet-induced thermogenesis, is the amount of energy expenditure above the resting metabolic rate due to the cost of processing food for use and storage. That is to say, you are actually burning calories while eating calories. The foods with higher TEF the are better for fat loss when you eat them.
TEF is strongly influenced by the total caloric content of the meals and the macronutrient composition (balance of carbohydrates, protein and fat) of the meals ingested. Meal frequency was previously thought to have great effect on TEF but this theory has been proven false.
Here are the details how to maximise it:
Protein induces the largest thermic effect of food response. You burn about 20-35% of the calories the food contains during digestion (so a 300-calorie chicken breast requires about 90 calories to break it down).
Protein is found in all animal products, including red meat, poultry, eggs, dairy, fish, and also to a lesser degree in vegetable sources of grains, legumes, nuts and seeds. Each gram of protein has 4kcal. Eat some protein with every meal and snack, at least one gram of protein per kilo of body weight, spreading it evenly throughout the day.
At 4 kcal per gram, just like protein, carbohydrate-rich foods have a TEF of 5-30%. Although lower compared to protein, carbohydrates is an important nutrient for intense physical activity (take heed if you are going to gym for serious workouts or run at intense pace) and some daily functions. Do you know that your brain needs about 50 grams of glucose just for normal functioning? If you do not supply such minimal amount, you will develop cognitive issues. Too much is counterproductive too.
Fruits, vegetables, and whole grains are much healthier than processed carbohydrates like sweets, soft drinks and pastries. The former have a TEF of about 20% and contain a lot of vitamins and minerals, phytochemicals and antioxidants. According to a study (1), people who eat processed food will cut their TEF in half, effectively reducing the amount of calories they burn throughout the day. Meaning, you will only burn half as many calories digesting and metabolizing processed foods compared to whole foods.
Besides burning more calories, veggies and fruits also help in the digestive process by stimulating various enzymes needed for proper nutrient absorption. Get a good portion of them in every meal.
Fat is the most concentrated source of energy (9 kcal per gram), has the lowest TEF (5 to 15%) which requires the least amount of energy to be digested but it can be your best friend in the war on body fat. Indeed, fat can help to burn help fat.
When you eat fat, they keep your satiety levels up for many hours. The low-digesting fat lowers the glycemic index of any food you eat, doesn’t raise blood sugar levels and controls the fat-storing hormone insulin. Further, eating fat has a great hormonal effect and has shown to actually boost your resting metabolism.
The type of fat you eat matters most. Most of your fat intake should come from monounsaturated and Polyunsaturated types like: Olive oil/Olives, Avocados, Peanuts, Tree nuts, Omega-3 Fatty Acids such as those found in Oily Fish (Salmon, sardines, mackerel) and seeds (chia, hemp, flax, pumpkin, sesame).
An irregular meal pattern (i.e. 3 meals on one day, 7 meals the next day, 2 meals the next day, etc...) has been shown to induce a significantly lower thermic effect of food than a regular meal pattern (i.e. a consistent 4 meals per day) that has the same total amount of calories. So, please do not skip meals (which will also negatively affect the RMR) and eat at regular intervals.
If weight loss is your goal, besides increasing your Resting Metabolic Rate and implementing other factors, you should choose your food wisely to take advantage of the 'calorie-burning' effect of eating. Aim for a serving of high quality Protein, non-processed Carbohydrates (especially if you are training hard) and healthy Fat at regular intervals everyday. No doubt this strategy impact the energy expenditure the least, but hey, everything counts and nothing should be left out of the equation right?
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1. Barr S. B and J. C. Wright. 2010. “Postprandial Energy Expenditure in Whole Food and Processed Food Meals: Implications for Daily Energy Expenditure.” Food and Nutrition Research 54: 5144.