This article will look at how ketogenic, moderate to high carbohydrate, and high protein diets effect athletic performance.
Why it Matters
Most high level or elite athletes will turn to their diet when looking to improve body composition and performance. Their body type and sport will most likely determine which diet will benefit them the most.
Whether you are an athlete, coach, or everyday person just getting into exercise or looking to switch things up, it is important to understand how different diets will impact your performance or that of your athletes.
- Nutrition is highly individualized and because of that there is not a one size fits all kind of diet out there.
- In general, recreational athletes can typically meet daily carbohydrate needs by consuming a normal diet (i.e., 45–55% CHO [3–5 g/kg/day], 15–20% PRO [0.8–1.2 g/kg/day], and 25–35% fat [0.5–1.5 g/kg/day]).7
- For building and maintaining muscle mass, an overall daily protein intake of 1.4–2.0 g/kg/d is sufficient for most exercising individuals.7
Ketogenic Diet & Performance
The ketogenic diet has become very popular amongst endurance athletes and athletes who require weight management due to its known ability to improve body composition without hindering performance. The original ketogenic diet (KD) is known as 80% of daily energy intake from fat, 15% protein, and 5% carbohydrate.1 Therefore, it is a low-carbohydrate diet that emphasizes the intake of fat over carbohydrates to induce the metabolic switch from burning carbohydrates to burning fat. This will have favorable body compositions effects and may be ideal for athletes in weight category sports.
Athlete’s in sports which require weight management should consider a long-term planning approach to KD and make sure they give at least two weeks for adaption to avoid any negative effects on performance.1 However, some studies have shown athletes utilizing a high fat, low-carbohydrate approach, see a reduction in maximal aerobic performance and a negative effect on performance when exercise intensity exceeds 70% of V02max.2,3,4,5
Additionally, this study showed that mean body weight was reduced by 4 kg or 8.8 lbs, and mean time to exhaustion dropped by 2 min in five (one male, four female) New Zealand endurance athletes who adopted a non-calorie controlled KD for 10-weeks. Although, other performance outcomes showed mean reductions, with some increases or unchanged results in two individuals.
Thus, a low-carbohydrate approach like the KD may be beneficial for improving body composition without inhibiting performance in most athletes. However, like everything else in regards to nutrition, it is highly specific and based on the individual as to how well an athlete will benefit from a low-carbohydrate approach. The KD would also help those who are wanting to lose weight and improve blood biomarkers, as well as those in the clinical population fighting chronic diseases.
Moderate to High Carbohydrate Diets
Moderate to high carbohydrate diets are typically reserved for anaerobic athletes and most team sports. It also depends on the activity and duration of the activity as endurance athletes can have anywhere from 6-10 g/kg of carbohydrates and strength athletes’ may need only 4-7 g/kg of carbohydrates.6
In general, recreational athletes can typically meet daily carbohydrate needs by consuming a normal diet (i.e., 45–55% CHO [3–5 g/kg/day], 15–20% PRO [0.8–1.2 g/kg/day], and 25–35% fat [0.5–1.5 g/kg/day]).7 However, athletes involved in moderate and high-volume training need greater amounts of carbohydrate, (e.g., 2–3 h per day of intense exercise performed 5–6 times per week) typically need to consume a diet consisting of 5–8 g/kg/day or 250–1200 g/day for 50–150 kg athletes of carbohydrate to maintain liver and muscle glycogen stores. Whereas, athletes involved in high volume intense training (e.g., 3–6 h per day of intense training in 1–2 daily workouts for 5–6 days per week) may need to consume 8–10 g/day of carbohydrate (i.e., 400–1500 g/day for 50–150 kg athletes) in order to maintain muscle glycogen levels.7
Thus, moderate to high carbohydrate intake, as listed above, should be reserved for highly active individuals and elite athletes. The general recommendation for carbohydrates or a low-carbohydrate approach is best suited for the general population or those trying to lose weight.
High Protein Diet
Furthermore, for building and maintaining muscle mass, an overall daily protein intake of 1.4–2.0 g/kg/d is sufficient for most exercising individuals.7 For athletes in a hypocaloric phase, higher protein intakes (2.3–3.1 g/kg fat-free mass/d) may be needed to maximize the retention of lean body weight. Furthermore, higher protein intakes (> 3.0 g protein/kg body weight/day) when combined with resistance exercise may have positive effects on body composition in resistance trained individuals (i.e., promote loss of fat mass).7
However, this study showed that when highly experienced resistance trained males consumed a high protein diet (2.6 ± 0.8 and 3.3 ± 0.8 g/kg/day of dietary protein) with a mean protein intake of 2.9 ± 0.9 g/kg/day over a 4-month period, there were no significant changes in body composition or markers of health in either group (control vs high protein group). Additionally, there were no side effects (i.e., blood lipids, glucose, renal, kidney function etc.) regarding high protein consumption.
Therefore, recommended protein intake is specific to the individual, as is carbohydrate and fat intake, but the general recommendations can be seen as a starting point for the various sports and activity levels.
Example Diet for an Olympic Hopeful
The following is an actual nutrition plan for a female track & field athlete who is training to qualify for the 400 m sprint in the 2021 Olympics. She is an elite level athlete fresh out of college with over eight years of training, specifically in the 400 m sprint. At the time this was designed she weighed in at 138 pounds with a goal running weight of 134 pounds, at 5’8.
This example is from she was ending her offseason strength training and was transitioning from cutting weight to improving performance. Her calories were at 2,445 kcal a day (2,695 kcal/day to maintain) to induce mild weight loss of .5 lbs a week. This was to avoid any loss in muscle and inhibit any training adaptations.
Below is a snippet of her day of eating for a scheduled anaerobic training run followed by a strength training session (both low volume). You will notice her carbohydrates are higher before and after training, as well as at night to help support training, promote sleep, and recovery. Protein is pretty even to help regulate glycemic variability, recovery, and muscle protein synthesis. The fat is just high enough to keep her from becoming too lean and effecting hormone regulation and performance. Fat is lower around her training to allow for faster carbohydrate utilization and recovery. She also has a separate supplement and micronutrient plan with specific foods that are built into this, but are not shown due to space and given length of this article.
|Thursday (anerobic run + lift)|
|Breakfast: 2 hours before Run Post-Run and lift: Immediately|
|30 grams of protein: See Foods (3.5 oz) 1 scoop creatine 5 g (recovery)|
|40 grams of starchy carbs: See Foods (sweet potato) 1 scoop Amino Acids 7.7 g|
|15 grams of healthy fat: See Foods (avocado) 1 scoop catalyte (hydration)|
|Lunch: 1-2 hours after Run Workout Snack: 2-4 hours later|
|30 grams protein (3.5 oz) 20 grams protein (whey protein shake)|
|80 grams of starchy + non-starchy carbs (sweet potato, kale, spinach) 20-30 grams carb: Fruit|
|15 grams of healthy fat (avocado) 30 grams healthy fat (nuts)|
|Dinner: 2-4 hours later Pre-bed time snack: Finish this at least 2 hrs before bed|
|30 grams protein 20 grams Whey protein|
|80 grams carbs starchy + non-starchy 40 grams dextrose|
|20 grams of healthy fat 20 grams healthy fat|
|Total / kcal|
|130 g PRO / 520 kcal – 20%|
|270 g CHO / 1,080 kcal – 42%|
|100 g Fat / 900 kcal – 35%|
|Total kcal: 2,550 kcals +/- 40 kcals (supplements)|
What works for one individual may not work for the other so it is important to go into any diet with an open mind and an understanding of what you are trying to achieve.
The above example is meant to help show how all the information within this article is put into use. While this example used a moderate to high carbohydrate diet you use it as a guide to help structure other diets for various goals.
Finally, this was not an exhaustive article by any means but will at the very least provide you with an overview to help direct your diet decision making for yourself or if you are a coach, your athletes.
Jon Esposito MA, CSCS, CISSN, USAW