Why Am I Gaining Weight Doing HIIT? 7 Real Reasons and How to Fix It
You're doing HIIT but gaining weight? It's not your fault-here are the 7 real reasons why and exactly how to fix them without quitting your workouts.
Read More
Why HIIT Makes You Gain Weight: The Real Reasons Behind the Scale
When you hear HIIT, High Intensity Interval Training, a workout style that alternates short bursts of all-out effort with brief rest periods. It’s sold as the fastest way to burn fat, boost metabolism, and get lean. But if you’ve been doing HIIT and the scale keeps going up, you’re not alone—and it’s not because you’re doing it wrong. It’s because your body is responding to stress, not just sweat. Many women, especially those with curvier bodies, start HIIT thinking it’s the magic bullet. But what if the very thing meant to help is actually pushing your body into survival mode?
One big reason HIIT, High Intensity Interval Training, a workout style that alternates short bursts of all-out effort with brief rest periods leads to weight gain isn’t about calories burned—it’s about cortisol. When you do HIIT too often, your body treats it like a threat. Your adrenal glands pump out cortisol, the stress hormone that tells your body to hold onto fat, especially around your belly. This isn’t theory—it’s biology. Studies show that overdoing high-intensity workouts raises cortisol levels in women more than in men, and that’s a problem if your goal is fat loss. You’re not gaining fat because you’re eating too much. You’re gaining it because your body thinks it’s under siege.
Then there’s the recovery gap. HIIT is brutal. It tears down muscle, drains energy, and taxes your nervous system. If you’re doing it five days a week while juggling work, kids, or stress, your body never gets a real chance to rebuild. Instead of getting leaner, you’re stuck in a cycle of fatigue, cravings, and water retention. And let’s not forget: when you’re exhausted, you move less outside of workouts. That daily walk? Skipped. The stairs? Taken by elevator. Your total daily movement drops—and so does your calorie burn.
Another hidden factor? Muscle gain. HIIT can build lean muscle, especially in the legs and core. Muscle is denser than fat. So even if you’re losing inches and your clothes fit better, the scale might not budge—or it might creep up. That’s not failure. That’s transformation. But if you’re only looking at the number, you’ll miss the real progress: stronger arms, better sleep, less bloating, more energy.
And here’s the truth most trainers won’t tell you: yoga, a mind-body practice that improves flexibility, reduces stress, and supports recovery through controlled movement and breath might be the missing piece. Yoga doesn’t burn 500 calories in 30 minutes, but it lowers cortisol, improves digestion, and helps you tune into hunger cues. It’s not the opposite of HIIT—it’s the balance it needs.
If you’ve been doing HIIT and the scale won’t move, it’s not about doing more. It’s about doing differently. Cut back to 2-3 HIIT sessions a week. Swap one for a long walk. Add 10 minutes of breathing before bed. Eat more protein and less sugar. Sleep like your life depends on it—because it does. Your body isn’t broken. It’s just asking for a different kind of care.
Below, you’ll find real posts from women who’ve been there—people who thought HIIT was the answer, only to discover the real keys to lasting change. No gimmicks. No quick fixes. Just what actually works when your body’s had enough.