Keto flu symptoms and side effects can include feeling tired, having difficulty sleeping, digestive issues like constipation, weakness during workouts, being moody, losing libido and having bad breath. Fortunately, these side effects don’t affect everyone and often only last for 1–2 weeks. (And yes, you CAN build muscle on keto.) Overall, symptoms go away as your body adjusts to being in ketosis.
It’s not always about how much you eat, but the nutritional balance of carbohydrates, fats, and protein in what you’re eating. Endurance athletes need extra carbs to fuel their rides, fat to feel satiated, and protein to repair your muscles post-workout. It usually isn’t necessary to make radical adjustments to achieve this balance—small changes work best. For instance, don’t eat a whole bowl of chili with meat. Instead, fill half the bowl with brown rice, then ladle a small amount of chili on top. You can also try substituting fat-free yogurt for sour cream and fruit for sweets.