Intermittent fasting (IF) is a trending method to lose weight and remain healthy. Intermittent fasting exercise is welcomed, healthy, and has many benefits when you know how to do it. Still, you may need help to safely maintain a workout routine while intermittent fasting. You must understand what happens to your body during IF and exercise and know how it’s safe to follow a workout routine.
Know what happens to your body during IF to understand whether or not you can exercise. Your body experiences changes during IF, including ketosis, autophagy, and metabolic switching.
Johns Hopkins Medicine explains metabolic switching (15).
Metabolic switching or ketosis is when your body’s metabolism runs out of glycogen or glucose to burn, turning to the fat stores instead. It encourages your body to start burning fat as the primary fuel source.
Dr. Sruthi further explains how autophagy initiates with fasting for hours daily (18). Autophagy allows cells to regenerate and create new ones, even reversing aging. The most popular IF is the time-restricted 16:8 method, where you have a 16-hour fasting period.
Exercises before, during, and after the 8-hour fuel window require tips, facts, and planning.
Read More: Fasting Detox: Foods And Drinks To Detoxify Your Body Safely
Exercise and IF are safe for most people. However, Johns Hopkins Medicine explains how exercise and IF aren’t safe without a doctor’s guide for the following (15):
Understand how each fasting exercise appeals to different goals to plan safe routines. Let’s see whether aerobic and strength training is safe for IF.
Cambridge University found that fasted cardio workouts improve your chances of weight loss (7). Meanwhile, they found that fasting cardio is safe for healthy individuals. The Guangxi Normal University published a study explaining the body processes (17).
First, fasted cardio increases insulin sensitivity, which is great for healthy individuals but not type one diabetics. Furthermore, the biochemical changes also revealed how some people’s protein becomes a fuel source instead of glycogen or fat (17).
High-intensity aerobic workouts can burn protein while you try to lose weight. It isn’t safe or suitable for anyone trying to maintain muscle mass. Low-intensity aerobic exercises during fasting windows don’t affect muscle mass but won’t increase it either (17).
In summary, fasted cardio is safe for losing weight, maintaining fitness levels, and speeding up your metabolism as a healthy individual.
Strength training and intermittent fasting can work if you know how to do it safely. The Swinburne University of Technology studied the effects of IF and resistance training (16). Muscle-building isn’t probable during intermittent fasting.
However, following simple safety guidelines preserves your muscles (16). Intermittent fasting can turn protein into a source of fuel. Dr. Carol DerSarkissian explains how muscles need protein to build mass and strength (19).
You must refuel your body with protein before and after workouts to sustain muscle mass during IF. Otherwise, it won’t be safe to exercise during IF. Additionally, Better Me strongly recommends adding carbs for muscle growth, even during IF (6).
In summary, high-intensity, muscle-building, HIIT workouts, CrossFit, and resistance training are safe. However, you must add carbs and protein as fuel sources to protect the muscles.
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Safety is the primary concern before you begin exercising while intermittent fasting. Some tips can help you achieve safe workout routines while you enjoy the many health benefits of intermittent fasting (11). Follow these tips to combine exercise safely with IF:
Timing exercise with IF matters for weight loss or muscle mass maintenance. In addition, choosing the right IF routine will help you benefit from timing exercises correctly. The Cleveland Clinic suggests using one of the four popular IF schedules (12):
The best IF is 16:8 or 14:10 if you want to use any workout. However, the University of Rennes found incredible benefits to morning workouts and IF (8). Those who exercised early in the morning in a fasted state had:
Furthermore, let’s not forget how Cambridge University confirmed better weight loss during fasted-state exercises (7).
Consider safety concerns when choosing to exercise during intermittent fasting. Let’s understand which fasting methods and exercises to combine to ensure you have suitable workout routines matched to your fasting schedule.
Registered Dietician Nutritionist Miho Hatanaka suggests aerobic and low-intensity workouts during fasting (10). So, use Cleveland Clinic’s low-intensity exercises during any fasted state on all the IF methods or right before breaking a fast (4):
Read More: Intermittent Fasting For Women Over 50 For Healthy Aging
Hatanaka also recommends anaerobic exercises to build muscle during IF eating windows (10). Follow the tips to eat protein and carbs around your workout. However, Dr. Jabeen Bedum suggests muscle-building exercises, which you can enjoy during eating windows (3):
Registered Dietician Nutritionist Miho Hatanaka reassures it’s ok to exercise during intermittent fasting (10). However, planning your exercises and meals for maximum effect is essential. Also, you shouldn’t exercise with IF if you’re pregnant or have type one diabetes.
Cambridge University found fasting aerobic exercise and intermittent fasting can help you lose more weight (7). Low-intensity cardio workouts can support the metabolic change to burn fat and glycogen for fuel. Fasting exercise with IF speeds up the weight loss benefits.
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Registered Dietician Nutritionist Miho Hatanaka suggests timing your workouts according to your IF routine (10). Only use low-intensity aerobics during fasting and high-intensity exercises during your fuel windows. That way, you safely time your IF exercises.
Fitness expert Daniel Bubnis recommends timing your exercises before, after, or during eating windows (9). Exercise before fasting to lose more weight. However, train during or after starting your fuel window to maintain muscle mass.
Intermittent fasting and workouts are safe when you follow tips, guidelines, and timing suggestions. Plan your workout routine accordingly. Use the correct method, plan which exercises to use on which days, and thrive with weight loss or muscle mass.
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