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Nutrition 101: Energy Balance

Posted on avril 02 2018

Eric Helms, MS, MPhil, CSCS, USAW L1

1. Whether gaining or cutting, determining your current calorie requirements is the first step in setting up a nutrition plan.

2. Mass gain or loss will be determined by your calorie consumption relative to your calorie requirements: more = gain, less = loss.

3. Despite the ‘3500-calorie rule’ being imperfect, is a practical way to determine your calorie requirements for weight maintenance, as well as your ideal rate of gain or loss.


Energy balance refers to the balance of energy expended, versus energy consumed. It is the incontrovertible law of gaining and losing mass since your body is beholden to thermodynamics. When discussing dietary intake, we usually use energy and calories interchangeably. To successfully gain or lose tissue you must manipulate your diet and/or activity to achieve an energy surplus or deficit, respectively (to remain the same weight, you must be balanced or in equilibrium). To do so, you should determine your current energy requirements. You might be familiar with “the 3500-calorie rule”; stating that 1 lb of fat contains roughly 3500 calories [1]. Thus, if you create deficit of 3500 calories you should lose 1 lb of body fat (assuming it’s all fat). Let me state up front this “rule” isn’t perfect, as not all weight gained or lost is fat and energy expenditure changes over time [2]. However, this relationship is still a useful aid to estimate the energy needs relative to your goals.

Most people, simply use a total daily energy expenditure (TDEE) calculator, in which an equation using your age, height, weight, body composition and sex determines your energy expenditure without activity. Then, you select an “activity factor” to multiply your basal energy expenditure by to determine your current maintenance caloric needs. However, TDEE has many components including the cost to metabolize and digest the food you eat, the energy you burn in training, subconscious physical activity, non-exercise activity, and TDEE is also adaptive in the sense that to some degree it can increase in response to overfeeding and decrease in response to underfeeding. Therefore, there is a great deal of individual variation in TDEE so, rather than use an equation I highly recommend collecting real data on yourself to determine your maintenance caloric needs.

Step one, obtain a digital food and bodyweight scale and an online account to a food tracking database (like MyFitnessPal, or others). Then, spend 2 weeks weighing and tracking your food when you prepare it and estimating your caloric intake even when you aren’t preparing it. In conjunction with tracking calories, step on the scale every morning, nude after using the bathroom and before you eat or drink anything. While that may seem like a lot of “prep” work, these controlled conditions will allow you to record your bodyweight (which can fluctuate 1-3% daily) with minimal “outside” influence. 

Next, you will compare the 7-day average bodyweights of week 1 to week 2 to determine the amount of weight gained or lost. Hypothetically, if you gained 1 lb of fat in a week, you should be, on average, consuming ~500 calories more than your maintenance per day (as 7 days x 500 calories = 3500). More likely though (unless you are currently cutting or bulking), you are close to maintenance. So, for a more realistic example, if you only gained 0.2 lbs, you simply multiply 3500 x 0.2 which is 700 calories. Meaning, in this example you are in a weekly surplus of ~700 calories or a daily surplus of 100 calories (700 calories divided by 7 days). Now, compare your average calories over the 14 days and subtract the surplus from that amount to determine maintenance: for example, if your average intake over 14 days was 2100 calories, you know maintenance is roughly 2000 (2100 – 100 calories).

But, what if your goal is gaining muscle? We’ve established ~3500 kcal is the energetic value of 1 lb of fat but, what about the caloric value of muscle? This is where things get interesting (and potentially confusing). A pound of hydrated muscle is only about one third protein, the rest is minerals and water! So, there are only ~800 calories in a pound of muscle [1]. However, while fat can be stored at almost no caloric cost, muscle mass requires calories to power the processes to synthesize new tissue. Also, even when doing things right (especially for lifters who are not overweight and not novices), you will probably gain both fat and muscle. Combine this reality with the metabolic cost of creating muscle tissue, and the “3500 calorie rule” actually holds up decently well for setting up your diet for weight gain or weight loss [3]. This is not to say that a pound of muscle has 3500 calories in it. Rather, you may have to increase your calories more than expected to gain muscle because the very process of building muscle increases caloric requirements. This along with increases in non-exercise activity energy expenditure (i.e. fidgeting, talking with your hands, dancing to any and all music) that occur in some people when in a caloric surplus, may be why weight gain is sometimes less than expected after a caloric increase [4].

Once you understand the energy balance relationship to body mass and can determine your own maintenance calories, then you can set your calories according to your goals which I will cover in Nutrition 101:  The Art of Balancing Energy Intake for Body Composition and Performance.


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  1. Hall, K.D., What is the required energy deficit per unit weight loss? Int J Obes, 2007. 32(3): p. 573-6.
  2. Hall, K.D. and C.C. Chow, Why is the 3500 kcal per pound weight loss rule wrong? International journal of obesity (2005), 2013. 37(12): p. 10.1038/ijo.2013.112.
  3. Williams, M.H., Nutrition for health, fitness, & sport. 2005: McGraw-Hill Science Engineering.
  4. Levine, J.A., N.L. Eberhardt, and M.D. Jensen, Role of Nonexercise Activity Thermogenesis in Resistance to Fat Gain inHumans. Science, 1999. 283(5399): p. 212-214



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