Starting a workout routine after bariatric surgery can be transformative—but also challenging if you’re not properly fueling your body. Here’s why calories matter and how to set yourself up for success in the gym while staying aligned with your post-surgery health goals.

Why Calories Matter

Your body needs energy to function, especially during physical activities like cardio and weightlifting. After weight loss surgery, your caloric intake is significantly reduced—often around 600-800 calories per day during the early stages. While this calorie restriction supports weight loss, it can hinder your ability to work out effectively if not adjusted appropriately as your activity level increases.

Signs You’re Undereating While Working Out

If your body isn’t receiving enough calories, it’ll let you know. Here are some common warning signs:

1. Fatigue During Workouts
   Running on an extremely low-calorie intake can leave you drained during exercise. Your legs might feel heavy, and pushing through your session may seem impossible.

2. Muscle Weakness
   Insufficient calories, especially protein, can force your body to break down muscle for energy. This makes strength training less effective and counterproductive.

3. Dizziness or Lightheadedness
   Low calorie intake combined with exercise may cause blood sugar levels to drop, leaving you feeling faint or unsteady.

4. Slow Recovery Times
   Without enough calories and nutrients to repair muscles post-workout, you’ll experience prolonged soreness and struggle to bounce back for your next session.

5. Plateaued Weight Loss
   Paradoxically, undereating while over-exercising can stall weight loss. Your body may interpret the calorie deficit as a threat, slowing your metabolism and conserving fat stores.

Why Undereating While Working Out Is Harmful

1. Your Body Prioritizes Survival
   With too few calories, your body focuses on basic survival functions rather than optimizing workout performance.

2. Increased Risk of Injury
   Low energy can compromise your form, increasing the risk of injury during exercises like weightlifting.

3. Muscle Loss vs. Fat Loss
   Inadequate calorie intake can cause muscle loss instead of fat loss, harming your metabolism and long-term strength.

4. Burnout
   Pushing your body too hard on an empty tank can lead to both physical and mental burnout, derailing your progress.

How to Fix It

1. Focus on Protein
   Post-op, prioritize high-quality protein to fuel muscle repair and energy. Aim for 60-80 grams per day, or more depending on your stage of recovery.

2. Gradually Increase Calories
   As your workouts intensify, gradually increase your caloric intake to support your activity level. Stay within bariatric guidelines to avoid overcompensating.

3. Listen to Your Body
   If you feel fatigued, dizzy, or unusually weak, adjust your diet or reduce the intensity of your workouts.

Key Takeaway

Exercise after weight loss surgery is about building strength, consistency, and confidence—not pushing yourself to the brink. Under-fueling is like trying to drive a car with an empty tank: it’s unsustainable. Focus on eating the right foods, getting enough energy, and listening to your body to make your fitness journey a success.