Understanding Your Energy Deficit

  • By Amey Corson
    By Amey Corson Six Star Ambassador

Many people see fat loss as a frustrating, seemingly endless wrestling match with their bodies.

The behind-the-scenes process of fat loss is fascinating and complex. Knowing the players involved in the fat loss game can help you understand the ins and outs of the process and harness the control you have over influencing your progress to reach your goals.

We measure the energy stored in food in calories, and when we consume them (in the form of macronutrients: carbs, fats and protein), our bodies convert food into the energy we need to fuel everything we do, from breathing and sleeping to running and lifting weights. But we don’t always get to use those calories immediately, and when we take in excess energy, we store it for later – usually as fat. You may be familiar with this part!

That brings us to the burning question: how do you get rid of unwanted body fat?

The ins and outs of energy balance


Luckily, the answer is simple: create an energy deficit. Energy balance in your body goes in two directions: input and output1. Like a budget, you can think of yourself as being in a surplus or a deficit, and understanding this basic equation is your road map to achieving any fat loss goal.

For instance, let’s say you go on a trip to spend a few weeks lounging at a sunny, breezy poolside. You aren’t exercising, and you definitely aren’t getting as much daily activity as you normally would. On top of this, you’re enjoying lavish, pineapple-infused, umbrella-touting calorie bombs and way too much guacamole. Chances are, you’ll weigh in heavier when you get back, because you created an energy surplus by consuming more energy than you expended. (It’s worth noting that it’s not all fat, and there’s some water weight influx here, since every gram of carbs stored in your body carries three grams of water2.)

Now, let’s say you start exercising more often and cut back on the food. If you stay consistent, you may notice your clothes loosen and after a few weeks you feel leaner. Increasing activity and decreasing caloric intake are ways of creating an energy deficit, where more energy is used than consumed. In this state, you tap into the energy reserves in your body and start metabolizing fat3.

When you’re not in a surplus or deficit and your body composition is remaining about the same, you’re experiencing maintenance. Fluctuations in intake can result in maintenance if they average out from meal to meal, day to day, week to week, etc. We may over- or under-consume calories at a given meal, but the daily total may pan out to be a maintenance intake. A roundabout way of experiencing maintenance is when you make efforts to start exercising more, but unintentionally compensate for the energy deficit from exercise by consuming more calories and effectively “canceling out” the deficit from one variable with a surplus from the other4.

If a little is good, then a lot must be better?

Reducing the occurrence of calorie consumption above maintenance intake and improving diet quality has been shown to drastically increase the probability that a diet will be successful5. Although individual differences can play a big role in how fast your body composition will change on a diet, it’s generally accepted that creating a 3,500-calorie deficit results in about a pound of fat loss3. This is where it can be tempting to get caught up in the math: if you can cut more calories to cut more fat, why can’t you eat even fewer calories to burn even more of that unwanted fluff? You’ll find, as many have, that this logic runs you into the ground pretty quickly.

Your efforts are better spent honing in on your macronutrient intake to create a reasonable, below-maintenance intake. This gives you a strategic, sustainable way to manage your energy budget. The science behind this part gets heavy, but we’ve already learned the basics: it’s all about manipulating energy balance. Definitely take into account your daily activity too, when you design your deficit intake. Considering energy output as a variable is important whether you are looking to bulk or if your goal is fat loss.

One deficit to rule them all


A “reasonable deficit” implies cutting back on only what is necessary to achieve a realistic rate of body composition change. A 10% to 20% reduction in calorie intake has been shown to be as effective as more restricted diets in the long term6. Dieting on the most calories you can consume and still seeing results is advantageous from a physiological and psychological standpoint. This method keeps your wellbeing in mind and helps prevent large-scale hormonal and metabolic rate adaptations that can occur with extreme measures7. Studies indicate that the lean body mass you worked hard for can be threatened when calories are lowered too severely8. I think we can all appreciate that aggressively dropping calories and “crash dieting” is not reasonable or sustainable!

Move it to lose it


When diet and exercise work together in harmony to formulate your weekly deficit, you won’t have to sacrifice as many calories per week, since you are burning more from exercise as well. Increasing activity even by one gym session per week can significantly contribute to your deficit9. Research shows that routinely participating in an exercise regimen can, in turn, bolster your motivation to improve your diet habits and promote a greater sense of control over eating behaviors10. Win-win! There is give and take that can be capitalized on from both energy deficit variables to garnish your success. Optimizing dietary and exercise strategies to create an adequate deficit that is sustainable and fits your lifestyle and individual needs is key.

Individual response to a calorie deficit may vary due to unique physiology, weekly activity level and, of course, consistent adherence to your plan11. It can take time to find the “sweet spot” as far as macronutrient breakdown, activity level and personal dedication to the plan to achieve a satisfactory rate of body composition change. Rest easy knowing that your macronutrient intake program is designed with your success in mind.

The energy balance framework isn’t flawless, and neither are we. However, you can let this new knowledge give you confidence to actively impact your fat loss process. Go forth and dominate the deficit!


  1. Donnell et al., 2005. Is exercise effective for weight loss with ad libitum diet? Energy balance, compensation, and gender differences. Exercise and Sport Sciences Reviews. 33(4): 169–174.
  2. Campbell, B., 2014. Sports nutrition: Enhancing athletic performance. Boca Raton: CRC Press.
  3. Hall, K. D., 2007. What is the required energy deficit per unit weight loss? International Journal of Obesity. 32(3): 573–576.
  4. Dhurandhar et al., 2014. Predicting adult weight change in the real world: a systematic review and meta-analysis accounting for compensatory changes in energy intake or expenditure. International Journal of Obesity. 39(8): 1181–1187.
  5. Keller et al., 2016. Not merely a question of self-control: The longitudinal effects of overeating behaviors, diet quality and physical activity on dieters’ perceived diet success. Appetite. 107: 213–221.
  6. Das et al., 2009. Low or moderate dietary energy restriction for long-term weight loss: what works best? Obesity. 17(11): 2019–2024.
  7. Sumithran et al., 2011. Long-term persistence of hormonal adaptations to weight loss. N Engl J Med. 365 (17):1597–1604.
  8. Mero et al., 2010. Moderate energy restriction with high protein diet results in healthier outcome in women. Journal of the International Society of Sports Nutrition. 7(1): 4.
  9. Donnelly et al., 2009. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults. Medicine & Science in Sports & Exercise. 41(2): 459–471.
  10. Annesi, J., 2016. Weight loss and the prevention of weight regain: evaluation of a treatment model of exercise self-regulation generalizing to controlled eating. The Permanente Journal. 20(3): 4–17.
  11. Thomas et al., 2012. Why do individuals not lose more weight from an exercise intervention at a defined dose? An energy balance analysis. Obesity Reviews. 13(10): 835–847.
  • By Amey Corson
    By Amey Corson Six Star Ambassador

    Amey Corson is 28 years old and currently lives in Tampa, FL. She earned a Master’s degree in Exercise Science from University of South Florida, is an Air Force veteran, and a pro bikini competitor. She likes to think of herself as a hippie who became a physique enhancement nerd. Typical Gemini.
    She has been running her own online personal training business since 2014.


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