Calorie Deficits for Athletes Explained

Edited by: Danielle Abel

Athletes have special considerations when altering their body composition because daily energy intake and expenditure can impact their performance. To maintain optimal body functioning and performance, athletes may need to be mindful of not only the duration of time they focus on reducing body fat but also the severity of calorie restriction, also known as energy restriction. 

What is a Calorie Deficit?

A calorie deficit is simply consuming fewer calories per day than what you or your athlete expend, from the most basic level, it's a diet. However, we're not referring to those fad diets marketed to consumers with special names. A calorie deficit, or diet, can be achieved by several means, but in general, the most scientifically supported, & healthy way to diet for athletes is achieved by reducing calories consumed but keeping protein intake high. 

A calorie deficit seems pretty straightforward conceptually, but what makes calorie deficits so complicated is that getting into a calorie deficit can be difficult to achieve without first understanding the concept of maintenance calories, otherwise known as estimated total daily energy expenditure (TDEE). Placing an athlete into a calorie deficit will require you to understand where the athlete's intake should ideally be, which is achieved by estimating the amount of calories the athlete needs. If you need guidance on how to calculate maintenance calories, check out this blog. 

After you know the estimated maintenance calories, you can determine what percentage of calories you will reduce each day. Remember, if there is concern that the athlete may not be consuming enough energy daily, then a more accurate and detailed approach may be necessary; see below to learn more about pretracking. 

Pretracking Intake

A more time-consuming but accurate & individualized approach to calculating a calorie deficit is first to have the athlete track their intake for 7-10 days, referred to as pretracking, to determine if their intake is high enough (close enough to their estimated maintenance) for them to go into a cut without compromising function & performance. 

Instruct the athlete to keep their dietary habits the same (some degree of alteration is expected and has been recorded in the scientific literature, so just be mindful of this), trying to capture as much detail about their intake as possible:

• Foods and drinks consumed for meals & snacks
• Condiments, sauces, or oils consumed
• Alcohol intake as applicable (take the total number of calories on the nutrition label & divide by 4, and then track it in grams of carbs is the easiest way)

At the end of the 7-10 days of pretracking, calculate the average calories consumed by adding up each day's calories and dividing by the total number of days tracked. Hopefully, this number is close to their estimated TDEE. If so, then you could probably recommend a time-bound calorie deficit for the athlete. If the athlete's intake is below their estimated TDEE or is above, this article on maintenance calories might help you decide how to proceed. 

Notice we mentioned a time-bound calorie deficit above. For athlete's keeping their intake below their body's daily maintenance calories for too long has the potential to impact their performance negatively. So, choosing an estimated start and a stop date with your athlete is important. 

What to Reduce and Considerations on Food Volume

Once you know the athlete's estimated calorie intake, you'll want to achieve the calorie deficit by reducing the amount of carbohydrates and fats you or the athlete consumes weekly for a set amount of time (see more on "What to Do After the Diet" below). Remember, protein intake needs to stay high during this time and should not be reduced, or there is a risk of loss from lean body tissue, including bone, tendon, or muscle. 

• According to the National Strength and Conditioning Association (NSCA) protein intake should be kept between 1.8-2.7g/kg of body weight during an athlete's calorie deficit phases. 

Something that's important not to reduce is food volume for the athlete. Meaning, we want to keep the athlete's stomach as full as we can, to help them stay within the deficit targets. By keeping food volume high, it's likely that gastric hormones that sense the stretching and shrinking of the stomach won't be as activated, leading to more manageable hunger cues. If an athlete isn't constantly feeling hungry in the deficit, they'll probably be more likely to be successful at losing the desired amount of body fat.

Here's some ideas on swaps that can help athletes maintain higher food volume while in a deficit:

• Limit calories from liquids, consider low or zero-calorie beverages such as lower-calorie electrolyte drinks sweetened with non-nutritive sweeteners such as stevia or monk fruit
• Swap out easier-to-digest carbs, typically used during maintenance phases, like regular jasmine rice, for more fibrous, slower-to-digest foods like brown jasmine rice
• Increase the size of low-calorie and vegetable servings with each meal; for example instead of 1 cup of watermelon or green beans, increase to 2 cups
• Include protein with snacks, instead of mostly carbohydrate-based snacks desired to enhance performance; consider including protein with snacks during deficit phases to help slow digestion and increase satiety 

How Much and How Long to Reduce

There is no exact recommendation for the number of calories or percentage to reduce to achieve fat loss. In general, 3500 calories equals a pound, so reducing 3500 calories each week would mean reducing daily calorie intake by 500 calories. Although, a 500-calorie reduction may not be sustainable for some athletes.

We also need to recognize that various variables impact the rate at which an athlete burns calories, so usually, it's best to pick a conservative initial amount to reduce, measure adherence and progress, and adjust from there. 

Staying in a calorie deficit long enough until the desired weight (fat) loss goal is achieved is key. To adhere to the calorie deficit, there may be other considerations that would help determine the specifics of the calorie deficit phase:

• The season the athlete is in (ideally, fat loss phases might be best reserved for the offseason)
• Life or work stress that is also present, either in the present time or anticipated in the future
• How is biofeedback (is sleep, stress, , recovery, & digestion in a good place?)

In general, aiming to reduce a percentage of total calories per day for a weekly average works the best, in our opinion, and is the easiest to keep track of week to week. Plus, if you're working with a small athlete whose estimated TDEE is less than 2000 calories per day, dropping their intake using a percentage-based approach might be more desirable and easier to adhere to.

Here's a list of reductions and some considerations to go along with them to help you decide where to start:

• 10-15% reduction 
  • may be ideal for those with less fat to lose (5-10lbs)
  • limited or no dieting history
  • 4-8 weeks in duration with diet breaks at maintenance for 7-21 days as needed, may also be divided into sprints (2-3 weeks in a deficit, 1-2 weeks at maintenance)
• 15-25% reduction
  • may be ideal for those with a moderate amount of fat to lose (15-25lbs)
  • short or moderate dieting history (1-2 diets in the past 1-2 years)
  • 6-12 weeks in duration with diet breaks at maintenance for 7-21 days as needed, may also be divided into sprints (2-3 weeks in a deficit, 1-2 weeks at maintenance)
• 25-35% reduction
  • may be ideal for those with a larger amount of fat to lose (25 or more lbs)
  • moderate or long dieting history (3-4 diets or more in the past 1-2 years)
  • 8-16 weeks in duration with diet breaks at maintenance for 7-21 days as needed, may also be divided into sprints (2-3 weeks in a deficit, 1-2 weeks at maintenance)

Knowing that a variety of factors influences each person's metabolism, here are some considerations that might also be helpful when determining what percentage to start with:

• Age
• Body weight
• Muscle mass
• Body fat percentage
• Dieting history
• Frequency, intensity, and duration of exercise
• Non-exercise activity thermogenesis (NEAT)
• Thermic effect of food

Knowing these special considerations related to metabolism, if needed, it may be helpful to ask questions on an intake or evaluation form of your athlete that may give you clues on how the above factors might impact how many calories per day you or your athlete may need to reduce to see body fat reductions. 

Considerations for Cardio in Calorie Deficits

The word calorie deficit is a bit misleading because a calorie deficit can also be achieved through energy output. By this, you can also put yourself or an athlete into a calorie deficit by increasing the frequency, intensity, and duration of activity/exercise. 

For example, if you or your athlete would prefer to keep their intake relatively high during a fat-loss phase, you might consider a small % calorie deficit of 10% combined with added exercise each week. In many cases, the added exercise comes from aerobic or cardio-based activities since they don't add additional anaerobic fatigue to the body's muscles, compounding the stress on the athlete's body from training combined with the calorie deficit. 

Determining what added cardio per week might look like will probably depend on you or your athlete's preferences and the amount of available time each week. For example, both of these approaches might be options:

• Add on 2 sessions of low-intensity Zone 2 cardio (incline walking, rucking, biking, etc.) for 30 minutes each session (60 total minutes of Zone 2 cardio per week)
• Or, add on 1 session of low-intensity Zone 2 cardio for 30 minutes and 1 session of Zone 4/5 high-intensity cardio (ie: 15 seconds on, 45 seconds on intervals with a work-to-rest ratio of 1:3) for 10-15 minutes (30 total minutes of Zone 2 cardio and 15 total minutes of Zone 4/5 cardio per week)

You can also start with one approach, and adjust as necessary (see section below on How to Adjust a Calorie Deficit Over Time). 

Measuring Progress for Weight (Fat) Loss

It's easy to only refer to the scale when you or your athlete is in a fat loss phase. However, there are other ways to measure progress to determine if your calorie deficit goals are effective. Objective and subjective progress markers exist and can be used in conjunction with scale-based weight to evaluate progress:

• Body weight
• Measurements
• Progress photos

In general, we would recommend taking body weights at least 3-4 times per week to get a weekly average, avoiding singular highs and lows. Additionally, bi-weekly or monthly measurements and/or progress photos can also be helpful. 

How to Adjust a Calorie Deficit Over Time

An individual's metabolism will eventually adapt to reduced intake over time, slowing energy expenditure through the process known as adaptive thermogenesis. You may have heard of metabolic adaptation before; this is the layman's term for adaptive thermogenesis, as seen in scientific literature. So, to account for adaptive thermogenesis, you'll need to adjust intake or output over time. 

If you don't adjust intake over time, you or your athlete's calorie deficit numbers will eventually become their new maintenance calories, which can lead to reduced function & activity, as well as possibly unwanted weight gain (for more on this, see below on what to do after the diet). 

Depending on the situation and personal preferences, you can adjust intake up or down, and you can also adjust output up or down. The goal is to lose on the highest calories possible to prevent adaptive thermogenesis from taking over sooner than it eventually will. Being in the smallest calorie deficit possible will also make it easier to adhere to and likely will keep strength, performance, & function at a higher level for a longer period.

Below, we reference a few scenarios to help you decide what might be best for you or your athletes when it comes to adjusting a calorie deficit:

• Rate of loss stays between 0.5-1% for more than 2 weeks:
  • Keep calorie deficit & cardio goals the same, re-evaluate in 2 weeks to determine if any adjustments are needed
• Rate of loss is less than 0.5% for more than 2 weeks:
  • Is bodyweight being measured under the same conditions? (Same time of day, without clothing, etc.)
  • Is adherence to targets an issue? (Ie: Within 25-50 calories from goal on average daily?)
  • Is food & beverage intake accurate? (Is most food being weighed? Is alcohol being tracked accurately? Are bites, licks, & tastes being recorded? Are condiments, oils, & sauces being tracked?)
  • Consider dropping calorie intake by 50 calories per day (Ie: If prior calorie deficit goal was 1950 per day, drop to 1900 per day)
  • Consider adding on 15-30 more minutes of aerobic conditioning/low-intensity cardio per week (Ie: If the cardio goal was 120 minutes per week, increase to 135 or 150 minutes/week)
• Rate of loss is more than 1% for more than 2 weeks:
  • Consider increasing calorie intake by 15-20 per day (Ie: If prior calorie deficit goal was 1950, go up to 1965 or 1970 per day)
  • Consider dropping weekly aerobic conditioning/low-intensity cardio minutes per week by 15-30 (Ie: If the cardio goal was 180 minutes per week, drop to 165 or 150 minutes/week)

Keep in mind, we would recommend only making one adjustment at a time so it's easier to detect what may have elicited the change. 

What To Do After the Diet

In our experience, many athletes don't know you can't keep your intake low forever. Sadly, sometimes we see athletes who believe they need to stay in a calorie deficit to keep the fat off that they lost; however, this is not true. At the end of a dieting phase, you or your athlete's intake needs to be brought back up near their new estimated TDEE. 

Making the call to end the diet is a very individualized decision; here are a few considerations to be mindful of:

• Was there a scale/weight-based goal that was achieved? 
• Was there a certain aesthetic look that was achieved? 
• Was a certain timeline met?
• Has it been more than 16 weeks in total of dieting? (We've noticed that after 16 weeks, most athletes need a break and are ready to go to their new maintenance, at least for a while, even if they have more weight/fat to lose)

The key to bringing intake back up is going slowly. Especially after 3 or 4 months of dieting, if you bring intake right back up to the new estimated TDEE, it is likely that some unnecessary fat gain may occur. So, to avoid this, we recommend adding between 50-100 calories every 1-2 weeks until you get close to the new maintenance. 

Here are some considerations when trying to decide if you should hold or increase:

• How are hunger levels? 
  • If you/your athlete are extremely hungry, you may want to increase by 100 calories every week until the hunger subsides 
  • Whereas if you/your athlete aren't very hungry or are experiencing bloating, you may want to increase by 50 calories every 2 weeks until digestive function & hunger cues return
• Is there an upcoming event, race, or competition? If so, you may want to increase intake quicker. 

Knowing all of this detail now, hopefully, this article leaves you feeling a bit more prepared to tackle a calorie deficit for yourself or an athlete. 

Want access to more educational information & resources from the Movement System? Be sure to subscribe to our newsletter below for updates, exclusive content, and new offers.