10 signs that you’re not eating enough on weight-loss drugs

Robert Price | Last update: 11th June 2025

1. Constant fatigue or low energy

One of the first signs of insufficient calorie intake is persistent fatigue. If you’re feeling drained even after a good night’s sleep, your body may not be getting enough fuel. Incorporating energy-boosting foods like whole grains, nuts, and lean proteins into your meals can help combat this. For more information take a look at Top protein snacks to keep you full and fuelled throughout the day or How much protein do you need.

2. Frequent dizziness or light-headedness

Low blood sugar levels, caused by eating too little, can lead to feelings of dizziness or light-headedness. Keeping healthy snacks like fruit or granola bars on hand can stabilise blood sugar levels throughout the day and help you avoid these symptoms. For more insight on the signs have a read of Signs you’re not eating enough.

3. Difficulty concentrating

Struggling to focus or feeling mentally foggy may result from a lack of essential nutrients. Your brain requires a steady supply of glucose and other nutrients to function optimally. Including complex carbohydrates like oats or quinoa in your diet can help maintain mental clarity.

4. Muscle weakness or loss

Not eating enough can lead to muscle loss, as your body starts breaking down muscle tissue for energy. Prioritising protein-rich foods like eggs, fish, or tofu supports muscle mass and keeps you strong. Have a look at our article Losing weight, losing muscle? The risks.

5. Feeling cold all the time

If you’re constantly feeling cold, even in warm environments, it may be a sign that your metabolism has slowed down due to inadequate calorie intake. Consuming enough calories and including healthy fats like avocados and olive oil in your diet can provide the energy your body needs.

6. Hair thinning or loss

Hair loss or thinning can occur when your body isn’t receiving enough essential nutrients, such as the vitamins and minerals that help with hair health. Incorporating nutrient-dense foods like leafy greens, nuts, and seeds into your meals can help maintain healthy hair.

7. Mood swings or irritability

A lack of calories and nutrients can cause mood swings, irritability, or feelings of depression. Your body and brain need consistent nourishment to maintain emotional stability. Eating foods rich in omega-3 fatty acids, such as salmon or walnuts, can help regulate mood.

8. Irregular menstrual cycles

Not eating enough can disrupt hormonal balance, leading to irregular or missed menstrual cycles. If you notice this, see your doctor or consult with your healthcare provider to address nutritional deficiencies and hormonal health.

9. Digestive issues

Eating too little can slow down your digestive system, causing issues like constipation or bloating. Increasing your intake of fibre-rich foods like fruits, vegetables, and whole grains, along with drinking plenty of water, can support a healthy digestive system. For more tips see Practical solutions for constipation. 

10. Persistent hunger despite lack of appetite

Paradoxically, you might feel constant hunger even when your appetite is suppressed by weight-loss drugs. This could indicate that your body is still in need of essential nutrients. Planning balanced meals with a mix of proteins, fats, and carbohydrates ensures your body gets what it needs.

Ensuring you’re eating enough

If you’ve noticed any of these signs, it’s time to reassess your eating habits. Talk to your doctor about getting the support of a dietitian to create a meal plan that supports your weight-loss goals while meeting your body’s nutritional needs. Remember, weight loss is about balance, and nourishing your body is just as important as reducing calorie intake. 

Have you experienced these signs or found solutions that work for you? Share your experiences with the SlimrChat community and learn how others are navigating similar challenges.