What You Should Eat Before and After HIIT Workouts, According to a Certified Athletic Trainer
Here are best practices for properly fueling and recovering from high-intensity interval training.
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High-Intensity Interval Training (HIIT) remain one of the most popular training styles, taking the No. 6 spot on the American College of Sports Medicine (ACSM) Top 20 Worldwide Fitness Trends for 2025 (it’s been in the top 10 since 2018). HIIT can be interpreted in myriad ways, which may be one of the reasons it’s so popular. But whatever method of HIIT you choose, there are some best practices for fueling and recovery. Here is a rundown of what HIIT is all about, common pitfalls and the best ways to fuel these wonderfully intense training sessions.
What Is High-Intensity Interval Training (HIIT)?
HIIT can be any type of workout where the exercise intensity alternates between bursts of high intensity and periods of recovery with lighter exercise or rest. These interval shifts allow for a higher average heart rate and calorie burn in a shorter period of time. This style of workout can be executed via circuit training, sprinting, cardiovascular equipment, free weights and even body weight exercises. Consistent and appropriate HIIT training over time has been linked to reduced body fat, increased muscle mass, weight loss and improved metabolic markers like reduced blood pressure and better blood sugar control.
Cortisol Connection
Cortisol is known as the “fight or flight” hormone. Levels of this naturally occurring adrenal hormone are typically highest in the morning and will decline throughout the day, but the body can also use cortisol to release stored energy and control inflammation in response to stressors like exercise. Some question the potential negative impact elevated cortisol may have on health and argue that HIIT training causes such elevations.
Research supports that consistent exercise can create positive cortisol responses through training adaptations. A study published in 2021 looked at the acute impact of one hit HIIT workout on cortisol levels and found that post-HIIT cortisol levels would increase but return to baseline after a 24-hour window, possibly indicating that an ideal recovery time between HIIT sessions is at least 24 hours apart. Another recent study further supports the impact that regular physical activity can have in reducing cortisol levels.
Exercise is stressful, but committing to a consistent exercise regimen will help the body adapt and avoid dramatic swings in cortisol levels. To help manage cortisol, it’s best to focus on a variety of exercise styles, including HIIT, strength and exercise with an increase flexibility component like yoga or pilates.
Women and men have different needs, habits and different physiological responses when it comes to exercise. Dr. Kelley Skye-Eagle, Assistant Professor of Dietetics at Arkansas State University researches the impact of high and low intensity exercise and draws attention to the fact that women tend to focus heavily on cardiovascular exercise and neglect strength training. This can cause more dramatic increases in cortisol levels, inhibiting fat loss. Based on her research, Skye-Eagle recommends alternating HIIT with strength sessions to help enhance cortisol adaptations and facilitate better training outcomes.
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How to Fuel HIIT Workouts
Fueling HIIT workouts properly is crucial to optimizing performance. Early morning exercise enthusiasts should opt for a meal or snack that is easily digestible with carbs and a limited amount of protein (10 grams or less) if workouts begin within an hour of waking up. Examples of these pre-workout snacks include a small smoothie (hold the protein powder), a piece of toast with jam, a small fruit and nut bar, peanut butter crackers or a small piece of fruit with a rice cake. Those that workout in the afternoon should eat meals regularly throughout the day and if needed, add a high-carbohydrate snack prior to exercise to provide some quick-digesting fuel.
No matter what time of day your HIIT training ends, follow up the workout with a recovery meal or snack that contains both protein and healthy carbohydrates. This can be a recovery product like a protein bar, protein shake or balanced meal depending on timing. At this stage, increase protein intake to about 30 grams to help muscles recover. Try four ounces of cooked lean meat or fish, which contains 28 grams of high-quality protein, and doesn’t require large portions to get that protein. One cup of Greek yogurt or two eggs with a 1/2-cup of cottage cheese will also get you to that goal easily. Add in some fruit or vegetables, and healthy carbs like rice, quinoa, sweet potato or whole-grain bread to round out the meal. If the workout was sweaty – and it probably was – be sure to replenish sweat losses with plenty of fluids and electrolytes. The more you lose, the more you need to replace.
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