How Your Diet Helps You Achieve These 3 Popular Fitness Goals

By Laura Schoenfeld, RD

You may have heard some version of the saying “a fit body is made in the kitchen.”

While your training choices play a big role in your ability to accomplish your fitness or body composition goals, your diet is truly more important than you might realize.

Many women who train regularly (and successfully) stick to a specific nutrition plan to support their health and fitness goals. Those that don’t often don’t get the results they’re looking for.

After working with hundreds of active women, I’ve seen a few major themes come up when it comes to fitness or aesthetic goals that women want to achieve.

These are the three most popular training-related goals:

  1. Lose weight and/or body fat
  2. Increase muscle size or definition (“getting toned”)
  3. Improve performance

Depending on which of these goals you’re working towards, your diet choices will need to adjust significantly to help you reach that goal.

Let’s talk about each goal individually, and how to adjust your nutrition strategy to work towards each one successfully.

1. Eating for Weight Loss or Fat Loss

For fat loss, the main thing that matters is if you are in a sustainable calorie deficit. This means you are eating slightly less than you are burning, and your body is tapping into stored body fat for the extra calories.

Keep in mind, there’s a sweet spot for a calorie deficit, and you won’t get better results by going more than a few hundred calories below your estimated needs.

In fact, going too low in your calorie intake can actually cause your weight loss to stall, and lead to other serious health issues that are caused by chronic malnutrition.

You can accomplish a moderate calorie deficit by eating slightly less, or exercising a bit more, or a combination of both. Just like undereating, overtraining can wreck your progress too, so be careful to monitor your recovery from workouts and take adequate rest days.

It’s somewhat normal for your performance in the gym, as well as your daily experience of health and wellness, to suffer during a fat loss protocol that involves a purposeful calorie deficit. But you need to be aware when you’ve crossed the line from mild discomfort and reduced performance to overt health issues and injury.

What about macros? You might be surprised to learn that going low carb or low fat doesn’t significantly impact weight loss results [1]. The main thing that matters if that you’re eating in a way that you can stick to for long enough to see progress.

So your exact macro ratio is less important than you think. Pick a macro balance that allows you to eat the foods you enjoy and support your particular style of training.

The one caveat about macros is that a high protein diet can definitely support your fat loss efforts while helping you maintain lean muscle mass during a period of lower calorie intake [2,3,4,5].

While you can pretty much tweak your carb and fat intake however you want, I’d encourage you to eat at least 20 to 30 percent of your calories from protein while in a deficit.

To stay in a deficit more easily, focus on eating lots of high quality proteins, especially meat, fish, poultry, and eggs. Emphasize plant-based sources of carbohydrates as much as possible, like sweet potatoes, potatoes, rice, beans, and plantains. Filling your plate with non-starchy veggies and leafy greens will help keep you more full when you’re eating in a deficit.

Finally, make sure you’re getting as many nutrient-dense foods as you can while eating in a deficit. A reduction in food intake can sometimes lead to inadequate nutrient intake. This can lower your metabolic function and lead to symptoms of nutrient deficiencies.

You can avoid this by taking a high quality multivitamin when eating for fat loss. Talk to your personal nutritionist or healthcare provider to find an appropriate multivitamin to use.

To sum up, the best way to lose body fat safely is maintaining a sustainable, moderate calorie deficit using a high protein, whole foods-based diet and following a smart training program that includes weight training.

If you’ve hit a plateau in your weight loss or fat loss progress, check out this post for ideas on how to break through any stalled progress.

2. Eating to Increase Muscle Size and Definition

Eating for “gains” in your muscle size, or to see more significant muscle definition, requires a very different approach than fat loss.

If your goal is to build muscle and see more definition in your individual body parts, you should be eating enough calories to maintain your weight at a minimum. If you want to gain more size or muscle mass, you need to be eating in a caloric surplus.

Just a few hundred calories above your maintenance needs, combined with strength training, can allow your body to put on more muscle mass than eating to maintenance alone. This is easier to do when your fat and carbohydrate intake isn’t restricted in any way.

Along with a caloric surplus, a high protein intake is also important for building larger, more defined muscles. For most women, 1.7 to 1.8 grams of protein per kilogram of body weight (or 0.77 to 0.82 grams per pound body weight) is effective. There aren’t any benefits of going above 2.0 g/kg (0.9 g/lb) daily when trying to build muscle.

For a 150-pound woman, this would be somewhere in the range of 115 to 135 grams of protein daily. This is completely doable using whole foods like meat, fish, poultry, eggs, dairy, and beans or legumes. But throwing in a protein shake post-workout can help you hit the higher end of your protein goals in a more appetizing way.

Use a high quality protein powder like hydrolyzed beef, grass fed whey, or organic pea protein to sneak in some extra protein if you’re having a hard time eating that much from whole food sources.

Nutrient timing is another important factor when trying to put on muscle mass. Now, you don’t have to slam a protein shake the minute you leave the gym. But try to have at least 20 to 25 grams of protein from food or protein powders within two hours of training for maximum muscle growth and recovery post-workout [6].

Pre- and post-exercise meals should not be separated by more than approximately three to four hours for optimal muscle growth from a strength training routine [7]. Assuming you train for about an hour, eat your pre-workout meal or snack about one hour before training. Then eat your post-workout meal or snack within one or two hours after your training session. This will optimize your muscle growth from the training you’re doing.

Afraid to Get “Bulky”?

I have an important aside for those of you ladies afraid to build muscle.

Many women say they want to get “toned” as part of their fitness and appearance goals. What that actually means it that they want to build muscle.

When women strength train with heavy weights, they frequently get better body composition results than they would if they were afraid to train in a way that would make them “bulky.”

I’d like you to consider two things: First of all, the term “bulky” is completely subjective. Your ability to build large muscles is largely genetic, and many women have to eat extremely large quantities of food and train with frequency and intensity to develop the kind of large muscles you see in a bodybuilding or CrossFit competition.

Second of all, if you’re unhappy with how large your muscles are getting, scale back the training and eat less. You can still train with heavy weights and eat a decent amount of food and not grow massive muscles that you’re uncomfortable with.

And even if you do get bigger, so what?

Many women want to develop bigger and stronger muscles, and have a different perception of what’s considered acceptable or desirable for their body to look like. There’s no rule that says you can’t have large muscles as a woman.

It’s your body, and it’s your business what kind of eating and training style you choose to support your fitness goals.

3. Eating for Improved Performance

Finally, let’s talk about my absolute favorite goal to base your nutrition around: eating for improved performance. Why is this my favorite?

First, it’s one of the only goals that supports optimal health as well. Your performance depends on your ability to eat, sleep, train, and rest in a way that optimizes your energy, hormone production, digestion, and stress levels.

Second, many women discover that by eating and training to optimize their performance, they “accidentally” improve their aesthetics as well. If we’ve got all the right pieces in place to see strength and endurance progress in the gym, our bodies often respond with stronger, more defined muscles, and a reduction in excess body fat.

Third, this goal is the most fun! Seriously! There’s nothing better than training in a way that boosts your body’s physical abilities and allows you to hit personal bests month after month.

Accomplishing physical goals that you’ve never done before is exhilarating, and most women find it far more empowering than seeing a lower number on the scale.

So how do you eat to boost performance?

First, eating a maintenance calorie amount is crucial for performing well in the gym. Undereating is one of the primary reasons why women stall in their performance improvements or actually see a loss of ability despite training hard.

You need to be absolutely sure you’re eating enough every day to continue performing well in the gym. And you might be surprised how many calories that requires! Check out this post to learn what your maintenance calorie needs might be.

Second, much like a muscle building goal, nutrient timing is incredibly important for optimum performance. As I mentioned before, your pre- and post-exercise meals should not be separated by more than four hours [7].

And while protein intake is important, your carbohydrate intake pre- and post-workout often plays a bigger role in how well you can perform at higher intensity, anaerobic training. Anaerobic workouts include weight lifting, sprints, or anything that requires shorter bursts of high intensity activity.

The main fuel you use for these types of workouts is carbohydrate. To maximize your performance at these types of training sessions, you need to be getting pre-workout carbohydrate at a minimum.

You should also be consuming carbohydrates within two hours post-workout to optimize glycogen synthesis [8]. Your body will hold onto that muscle glycogen until your next workout, allowing that stored glucose to fuel your next session.

Aim for 20 to 60 grams of carbohydrates within two hours of training for maximum glycogen synthesis and recovery from your training session. The lower end should be for women who are on lower carb diets, and the higher end for those on higher carb diets.

You can play around with post-workout carbohydrate intake to see what amount makes you feel the most energized after a tough session.

Remember, even if you’re on a lower carb diet, the pre- and post-workout window is the best time to bump up your carb intake for optimal performance without losing the benefit of your low carb intake. Your body will burn those carbs for energy during your workout, and store the post-workout carbs as muscle glycogen. This is exactly what you want when you’re training hard on a lower carb diet.

But Do I Really Need A Nutrition Goal?

Technically, no.

You can train hard as often as you’d like and you don’t have to necessarily be trying to accomplish anything specific. Some people just enjoy exercise and don’t need to be working towards a goal to stay motivated.

But if you’re training with any level of frequency or intensity, you should never ignore your nutrition. Even if you don’t have a goal in mind, it’s important to support your body’s recovery with your food choices.

If you don’t have a goal, I’d suggest following the recommendations for improving performance. That way you’re at least meeting your body’s basic needs for recovery and muscle repair post-workout.

Not sure how to set a goal that matters? Check out this article for tips on how to figure out what goals are most important to you!

No matter what your goal is, take the time to establish a healthy, evidence-based eating strategy that will help you succeed!

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About the author:  Laura Schoenfeld, RD

Laura Schoenfeld is a registered dietitian trained in functional medical nutrition therapy. She helps her clients identify and implement diet and lifestyle changes that will allow them to live their healthiest, fittest, symptom-free life, without being consumed by thoughts of food and exercise. She loves hikes with her dog, beach trips, live music, and heavy weight training. Find her at


  1. Gardner CD, et al.. Effect of Low-Fat vs. Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association with Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial . JAMA. (2018)
  2. Ebbeling CB, Swain JF, Feldman HA, Wong WW, Hachey DL, Garcia-Lago E, Ludwig DS. Effects of dietary composition on energy expenditure during weight-loss maintenance. Journal of the American Medical Association (2012) 307(24):2627-34
  3. Astrup A, Raben A, Geiker N. The role of higher protein diets in weight control and obesity-related comorbidities. International Journal of Obesity (2015) 39: 721–726
  4. Longland TM, Oikawa SY, Mitchel CJ, Devries MC, Phillips SM. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. The American Journal of Clinical Nutrition (2016) 103(3): 738-746
  5. Layman DK, Evans E, Baum JI, Seller J, Ericsson DJ, Boileau RA. Dietary Protein and Exercise Have Additive Effects on Body Composition during Weight Loss in Adult Women. The Journal Of Nutrition (2005) 135(8): 1903-1910
  6. Tipton KD, Phillips SM. Dietary protein for muscle hypertrophy. Nestle Nutr Inst Workshop Ser. 2013;76:73-84. doi: 10.1159/000350259. Epub 2013 Jul 25. Review.
  7. Aragon AA, Schoenfeld BJ. Nutrient timing revisited: is there a post-exercise anabolic window? J Int Soc Sports Nutr. 2013 Jan 29;10(1):5. doi: 10.1186/1550-2783-10-5.
  8. Ivy JL: Glycogen resynthesis after exercise: effect of carbohydrate intake. Int J Sports Med. 1998, 19 (Suppl 2): S142-5.

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