Thermic effect of food percentage of energy expenditure

Thermic effect of food percentage of energy expenditure

There are several components to the energy burned side of the energy balance equation: (1)

Resting energy expenditure (REE): The amount of energy the body uses, at rest, to fuel basic cellular-level metabolic activities and to keep the heart, lungs, kidneys, and other organs functioning. REE varies according to body size, body composition, age, gender, and genetic differences. In people who are not very active, REE represents about two-thirds of their total daily energy expenditure; in people who have very active jobs, REE may represent only half of their daily energy expenditure.

Thermic effect of food: It takes energy to digest, absorb, and store the nutrients from foodabout 10 percent of a persons total daily energy expenditure. Fat, carbohydrate, and protein each require different amounts of energy to be processed. Protein has the highest thermic effect, and fat has the lowest.

Thermoregulation: Keeping the body temperature steady requires energy. In general, clothing, shelter, and climate control systems help people maintain their body temperature within comfortable limits, so thermoregulation is only a very small part of daily energy expenditure.

Physical activity: Any intentional body movement that burns calories is considered physical activity. For most people, exercise makes up only a small part of the energy they spend on physical activity. The bulk of it is spent on other routine daily activitiesfrom fidgeting and walking to household chores and office workcollectively referred to as non-exercise activity thermogenesis, or NEAT. (2) Calories burned through NEAT vary quite a bit from person to person, depending on genes, occupation, and environment, and declining NEAT levels are thought to play a role in the obesity epidemic.

References

1. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Washington, D.C.: National Academies Press; 2005.

2. Levine JA. Nonexercise activity thermogenesisliberating the life-force. J Intern Med. 2007; 262:273-87.

Did you know, you can burn more calories just by eating certain foods? In the same way that a high intensity workout (HIIT) burns more calories after exercise compared to steady-state cardio, some food types can have an increased afterburn too, because of the energy it takes for your body to break it down.

This is called the thermic effect of food, with certain food types increasing metabolic rate after ingestion. In this blog, we explain how eating more metabolism-boosting foods with a higher thermic effect can help fast-track your health and fitness goals.

What is the thermic effect of food?

The thermic effect of food (TEF) is the amount of energy it takes for your body to digest, absorb, and metabolise the food you eat.

TEF makes up a part of your daily calorie expenditure (calories out), and usually represents about 10% of the caloric intake of healthy adults eating a mixed and balanced diet. So for example, if you expend 2000 calories in a day, around 200 of those will be burned just from eating food.

Certain food types such as protein and complex carbs have a higher thermic effect than fats or simple carbs because your body has to work harder to break it down, thus spending more energy and burning more calories.

Varying factors affect TEF, primarily the portion size of your meal and its macronutrient composition – protein, carbohydrates and fats – along with your age.

How do macronutrients alter the thermic effect of food?

The energy required to digest each macronutrient (its TEF) is measured as a percentage of the energy provided by it.

  • Fat provides 9 calories  per gram. Its TEF is 0-5%
  • Carbohydrate provides 4 calories per gram. Its TEF is 5-15%
  • Protein provides 4 calories per gram. Its TEF is 20-30%

So that means protein tops the charts as the most thermic macronutrient, with approximately 25-30% of the calories you consume from protein being used for digestion and metabolism.

This is why a high protein diet has a metabolic advantage over normal or low protein diets with the same amount of total calories and has been proven to keep you fuller for longer.

Top tip: If you find yourself hungry soon after breakfast try swapping your cereal for protein-rich eggs and oily fish to fire up your metabolism and keep your blood sugar on a level to avoid the mid-morning crash.

Carbohydrates are the next most thermic macronutrient, with a TEF of 5-15% depending on the carb source. There’s a reason we recommend complex carbs on our nutrition plans to give you sustained energy for your personal training sessions and throughout the day.

High fibre carbs digest more slowly and have a higher thermic response, packing in more nutrients and vitamins along the way.

Choosing wholegrain rice, pasta and bread over refined white variations where the vitamin-rich bran and germ are removed will keep you fuller for longer by reducing blood sugar spikes (and the hunger pang / energy crash that follows them) after meals.  

A 2017 study found participants increased their metabolism by more than 92 calories per day just by substituting refined grains for whole grains. Just sayin’!

Top tip: Swap your baked white potato with beans and cheese for a sweet one topped with tuna for an energising lunch that doesn’t bring the 3pm slump.

Dietary fats have the lowest thermic effect at approximately 5-10% and are the simplest to digest. That doesn’t mean you shouldn’t include fats in your diet – it’s just a case of choosing the right ones.

Fats play a vital role in maintaining healthy skin, hair and nails, protecting vital organs against shock and helping maintain body temperature. They can also be used as an energy source, and slow down the body’s insulin response to high sugar foods.

Good sources of fat to include in your diet are avocado, salmon, nuts, egg yolks and pumpkin seeds.

Top tip: Swap vegetable cooking oil with olive or coconut oil for a healthier fat alternative.

Read more about the different macronutrients and why they’re important on our blog, and see 5 easy everyday swaps you can do today.

Why is the thermic effect of food so important?

If you’re looking to lose body fat or build muscle it’s important to understand the thermic effects of protein and other food groups and how they work to fuel your body.

When we overeat we’re least likely to store excess calories from protein due to the higher thermic effect, followed by carbohydrates, and lastly dietary fats. This is another reason why protein is incredibly important in weight regulation. Try to hit at least 1.8g of protein per kg of body weight, as part of a balanced diet with plenty of whole foods and vegetables to help you reach your goals.

Don’t fall into the quick fix trap!

Trying low carb or low fat diets for weight loss may be tempting, but cutting or restricting food groups in this way just isn’t sustainable and won’t work in the long term.

Your body compensates for the calorie deficit by slowing down your metabolism and clinging on to each and every calorie you put into it, storing as fat.  

So the trick is to put yourself in a *healthy* and balanced calorie deficit for longterm sustainable results. Including more protein-rich foods (at the right time) with a higher thermic effect (i.e. lean meat, fish, eggs and legumes) will keep your body working hard so you can bask in the afterburn long into your day.

Specific dynamic action (SDA), also known as thermic effect of food (TEF) or dietary induced thermogenesis (DIT), is the amount of energy expenditure above the basal metabolic rate due to the cost of processing food for use and storage.[1] Heat production by brown adipose tissue which is activated after consumption of a meal is an additional component of dietary induced thermogenesis.[2] The thermic effect of food is one of the components of metabolism along with resting metabolic rate and the exercise component. A commonly used estimate of the thermic effect of food is about 10% of one's caloric intake, though the effect varies substantially for different food components. For example, dietary fat is very easy to process and has very little thermic effect, while protein is hard to process and has a much larger thermic effect.[3]

Factors that affect the thermic effect of food

The thermic effect of food is increased by both aerobic training of sufficient duration and intensity or by anaerobic weight training. However, the increase is marginal, amounting to 7-8 calories per hour.[1] The primary determinants of daily TEF are the total caloric content of the meals and the macronutrient composition of the meals ingested. Meal frequency has little to no effect on TEF; assuming total calorie intake for the days are equivalent.

Although some believe that TEF is reduced in obesity, discrepant results and inconsistent research methods have failed to validate such claims.[4]

The mechanism of TEF is unknown.[5]: 505  TEF has been described as the energy used in the distribution of nutrients and metabolic processes in the liver,[6] but a hepatectomized animal shows no signs of TEF and intravenous injection of amino acids results in an effect equal to that of oral ingestion of the same amino acids.[5]: 505 

Types of foods

The thermic effect of food is the energy required for digestion, absorption, and disposal of ingested nutrients. Its magnitude depends on the composition of the food consumed:

  • Carbohydrates: 5 to 15% of the energy consumed[7]
  • Protein: 20 to 30%[7]
  • Fats: at most 5 to 15%[8]

Raw celery and grapefruit are often claimed to have negative caloric balance (requiring more energy to digest than recovered from the food), presumably because the thermic effect is greater than the caloric content due to the high fibre matrix that must be unraveled to access their carbohydrates. However, there has been no research carried out to test this hypothesis and a significant amount of the thermic effect depends on the insulin sensitivity of the individual, with more insulin-sensitive individuals having a significant effect while individuals with increasing resistance have negligible to zero effects.[9][10]

The Functional Food Centre at Oxford Brookes University conducted a study into the effects of chilli and medium-chain triglycerides (MCT) on Diet Induced Thermogenesis (DIT). They concluded that "adding chilli and MCT to meals increases DIT by over 50% which over time may accumulate to help induce weight loss and prevent weight gain or regain".[11]

Australia's Human Nutrition conducted a study on the effect of meal content in lean women's diets on the thermic effect of food and found that the inclusion of an ingredient containing increased soluble fibre and amylose did not reduce spontaneous food intake but rather was associated with higher subsequent energy intakes despite its reduced glycaemic and insulinemic effects.[12]

Measuring TEF

The thermic effect of food should be measured for a period of time greater than or equal to five hours.[13]

The American Journal of Clinical Nutrition published that TEF lasts beyond six hours for the majority of people.[13]

References

  1. ^ a b Denzer, CM; JC Young (September 2003). "The effect of resistance exercise on the thermic effect of food". International Journal of Sport Nutrition and Exercise Metabolism. 13 (3): 396–402. doi:10.1123/ijsnem.13.3.396. PMID 14669938.
  2. ^ Cannon, B.; Nedergaard, J. (2004). "Brown Adipose Tissue: Function and Physiological Significance". Physiological Reviews. 84 (1): 277–359. doi:10.1152/physrev.00015.2003. PMID 14715917.
  3. ^ Christensen, Peter. "What is the thermic effect of food?". Retrieved March 28, 2005. Archived November 17, 2007, at the Wayback Machine
  4. ^ Granata, G. P.; Brandon, L. J. (2002). "The Thermic Effect of Food and Obesity: Discrepant Results and Methodological Variations". Nutrition Reviews. 60 (8): 223–233. doi:10.1301/002966402320289359. PMID 12199298.
  5. ^ a b Chaprapani U. and Satyanaryana. Biochemistry, 4th Ed. Elsevier India, 2013 ISBN 9788131236017
  6. ^ Edward F. Goljan (2013). Rapid Review Pathology. Elsevier Health Sciences. p. 174. ISBN 978-0-323-08787-2.
  7. ^ a b Glickman, N; Mitchell, HH (Jul 10, 1948). "The total specific dynamic action of high-protein and high-carbohydrate diets on human subjects" (PDF). The Journal of Nutrition. 36 (1): 41–57. doi:10.1093/jn/36.1.41. PMID 18868796.
  8. ^ Halton, T. L.; Hu, F. B. (2004). "The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review". J Am Coll Nutr. 23 (5): 373–85. doi:10.1080/07315724.2004.10719381. PMID 15466943. S2CID 28136289.
  9. ^ Segal, K. R.; Albu, J.; Chun, A.; Edano, A.; Legaspi, B.; Pi-Sunyer, F. X. (1992). "Independent effects of obesity and insulin resistance on postprandial thermogenesis in men". Journal of Clinical Investigation. 89 (3): 824–833. doi:10.1172/JCI115661. PMC 442927. PMID 1541675.
  10. ^ Camastra, S.; Bonora, E.; Del Prato, S.; Rett, K.; Weck, M.; Ferrannini, E. (1999). "Effect of obesity and insulin resistance on resting and glucose-induced thermogenesis in man. EGIR (European Group for the Study of Insulin Resistance)". International Journal of Obesity and Related Metabolic Disorders. 23 (12): 1307–1313. doi:10.1038/sj.ijo.0801072. PMID 10643689.
  11. ^ Clegg, M. E.; Golsorkhi, M.; Henry, C. J. (2012). "Combined medium-chain triglyceride and chilli feeding increases diet-induced thermogenesis in normal-weight humans". European Journal of Nutrition. 52 (6): 1579–1585. doi:10.1007/s00394-012-0463-9. PMID 23179202. S2CID 45846650.
  12. ^ JKeogh, J. B.; Lau, C. W. H.; Noakes, M.; Bowen, J.; Clifton, P. M. (2006). "Effects of meals with high soluble fibre, high amylose barley variant on glucose, insulin, satiety and thermic effect of food in healthy lean women". European Journal of Clinical Nutrition. 61 (5): 597–604. doi:10.1038/sj.ejcn.1602564. PMID 17164830.
  13. ^ a b Reed, GW; Hill, JO (Feb 1996). "Measuring the thermic effect of food". The American Journal of Clinical Nutrition. 63 (2): 164–9. doi:10.1093/ajcn/63.2.164. PMID 8561055.

Further reading

  • Glickman, N; Mitchell, HH (Jul 10, 1948). "The total specific dynamic action of high-protein and high-carbohydrate diets on human subjects" (PDF). The Journal of Nutrition. 36 (1): 41–57. doi:10.1093/jn/36.1.41. PMID 18868796.

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