Before you embark on the high-fat, low-carb keto diet, be prepared for some initial changes to your exercise routine. When your body goes into ketosis, you will notice that the energy burst you would normally count on to power through your workout may not be as high as normal. You may feel uncommonly fatigued when you hit the gym. You may get tired during your workouts faster than usual and you may not have the same endurance.
Deprived of the energy-boosting carbs, your body will start burning fat for fuel; as your metabolism shifts, exhaustion follows—at least at first. Expect a slowdown for the first two to four weeks of your keto diet. Fatigue and mental fogginess will be compounded by dips in your electrolytes as the diet flushes water out of your body. Feelings of nausea and headaches are all part of the symptoms that dieters call the keto flu.
Don’t get discouraged and don’t give up all exercise during this time. During the first week or two, go easy on yourself and try workouts of short duration and low-to-moderate intensity. Substitute low-intensity aerobic exercises such as yoga, jogging and bicycling while your body adjusts.
Pair low-intensity cardio with some stretching and stability exercises for a great keto-friendly workout plan.
Any kind of cardio exercise is a great choice for the keto diet lifestyle because cardio burns fat, which is the primary calorie source in a keto diet. Jogging, swimming, step aerobics and rowing are all good examples of low intensity cardio.
Cardio workouts not only promote weight loss but also improve brain function, relieve anxiety and stress and give you a better night’s sleep. Cardio will also help your muscles adapt to exercise and grow stronger.
Anaerobic exercises like lifting weights may be difficult at the start of your keto diet because these exercises rely on burning carbohydrates for fuel. Your body won’t have many carbohydrates to burn, and that can make lifting weights harder at first. Substitute 10 pound weights for 20 pound weights and cut back on the number of reps you would normally do for each exercise.
You may want to consider adjusting your keto diet if the standard version leaves you feeling wiped out. Two other options for the diet—a targeted ketogenic diet and a cyclical ketogenic diet—may work for you. The targeted ketogenic diet directs you to eat your daily net carbs just before your workout, while keto cycling allows you one or two days each week of “re-feed” days to eat higher-carb meals and boost energy levels back to normal. You would follow the standard keto diet for the rest of the week. The drawback to keto cycling is that you may take yourself out of ketosis on the days you consume more carbs.
While exercising on the keto diet can take some adjusting and may even prove more difficult the entire time you’re in ketosis, there is some good news for keto enthusiasts. There’s evidence that resistance training while you’re in ketosis may result in an increase in muscle gain.
A study of 25 men on a resistance training program revealed keto dieting resulted in more increases in lean body mass and lost body fat in the first 10 weeks. Those who were following the keto diet showed more lean body mass gains following the final week of the training program than men who were eating a traditional Western diet, according to a study published in the Journal of Strength and Conditioning Research.
The tradeoff for some keto dieters is finding that ketosis prevents exercise from feeling as pleasurable as it did before they went on the diet. Keep in mind that a combination of a balanced diet and regular exercise is also important for your weight-loss strategy. If the high-fat, low-carb diet discourages you from the workout you love after the first four weeks, you may want to look for a different diet.