Exercise and Caloric Expenditure

Total daily energy expenditure or TDEE are the total amount of calories you expend per day and include many components. Your body needs energy for basic function—hormone synthesis, maintaining membrane potentials, enzyme kinetics, etc. Simply put, this is the energy need to keep you alive, to keep your organs and cells working. This basic function is found in basal metabolic rate or BMR, and is the largest component of TDEE. Other components of TDEE include activities like getting dressed, cooking, walking to the car, and fall under the non-exercise activity thermogenesis, or NEAT component. As Americans we spend a lot of time in sedentary activity, like sitting and standing, and therefore; NEAT accounts for a fairly large percent of TDEE. The third component of TDEE is the energy expenditure required to digest, absorb and metabolize food, which is called the thermic effect of food, or TEF. TEF accounts for roughly 10% TDEE. Finally, EAT or exercise activity thermogenesis is the energy expenditure that accounts for structured exercise. In this figure EAT is fairly small, accounting for <10% TDEE. Now, this figure is not a representation of everyone. EAT can account for up 30% TDEE depending on your activity level, training intensity and volume of exercise. EAT is the most variable as day-to-day training for someone who is exercising can change. Not to mention, for the average person to increase EAT so it accounts for a larger percentage of TDEE is fairly difficult because people just don’t have time to exercise for 2-3 hours per day.

But lets take a step back for a second and look at BMR again. What accounts for BMR that we can change? Well, our body composition has a large impact on BMR, specifically our muscle mass. It has been well studied that muscle mass accounts for the largest percent of BMR [1,2]. Increasing muscle mass through resistance training increases BMR and can improve weight loss in numerous populations [3,4,5]. The bottom line here is that when you compare the EAT to BMR, BMR wins out and the goal, in my mind, should be to increase BMR by changing body composition—namely increasing muscle mass. For some, this might be simply adding an additional 5-10 lbs of muscle, which can go a long way to improve BMR and out health outcomes like insulin sensitivity, and blood lipid levels.

I am all about quality over quantity when it comes to exercise. Don’t look to exercise for hours on end 7-day per week. Have a solid training program that includes a dose of intensity and volume that suits your needs. Include large muscle groups by completing movements like back squats, deadlifts, pull-ups, strict press, and bench press. Aim to increase the size and stamina of muscle by completing 4-5 sets of 8 to 12 reps. You can also include high-intensity interval resistance training (HIIRT) into your workout routine. HIIRT has been shown to increase acute REE (or BMR) to a greater extent post exercise compared to traditional resistance training [6]. HIIRT might also include a CrossFit workout with programmed rest. One of my favorite workouts is a baseline workout called “Barbara.” One of the benefits of CrossFit is the combination of conditioning and resistance training, which can increase RMR, EAT and muscle mass.

“Barbara”

5 Rounds for Time:

20 Pullups

30 Pushups

50 Situps

50 Squats

-3 minutes rest between rounds-

Components of Total Daily Energy Expenditure (TDEE). BMR: Basal metabolic rate; NEAT: Non-exercise activity thermogenesis; TEF: thermic effect of food; EAT: exercise activity thermogenesis; REE: resting energy expenditure; NREE: non-resting energy expenditure.

Image from: http://www.jissn.com/content/11/1/7

1. Johnstone AM, Murison SD, Duncan JS, Rance KA, Speakman JR. Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine. Am J Clin Nutr. 2005;82(5):941-8.

2. Webb P. Energy expenditure and fat-free mass in men and women. Am J Clin Nutr. 1981;34(9):1816-26.

3. Ryan AS, Pratley RE, Elahi D, Goldberg AP. Resistive training increases fat-free mass and maintains RMR despite weight loss in postmenopausal women. J Appl Physiol. 1995;79(3):818-23.

4. Cullinen K, Caldwell M. Weight training increases fat-free mass and strength in untrained young women. J Am Diet Assoc. 1998;98(4):414-8.

5. Byrne HK, Wilmore JH. The effects of a 20-week exercise training program on resting metabolic rate in previously sedentary, moderately obese women. Int J Sport Nutr Exerc Metab. 2001;11(1):15-31.

6. Paoli A, Moro T, Marcolin G, et al. High-Intensity Interval Resistance Training (HIRT) influences resting energy expenditure and respiratory ratio in non-dieting individuals. J Transl Med. 2012;10:237.