As we introduce Mounjaro into our weight loss journey there are a few thing to consider like how to get more active or what to eat on Mounjaro, but how do you know if you’re eating enough?

If you’re using Mounjaro injections, you’ll know how powerfully it can suppress your appetite. That’s why it’s such an effective weight loss tool – and why around 500,000 people are currently taking it.

But what if you’re eating too little? This is a common concern among Mounjaro, users – and it is important you know the risks and the signs. Eating too little can have serious consequences for your health. It can also hamper your progress.

In this article, we explore why undereating can undermine your efforts to lose weight and live a healthy lifestyle. You’ll learn how to recognise the signs, and get practical ways to nourish your body – while still losing weight.

The Dangers of Eating Too Little on Mounjaro

Eating too little can be devastating for your body. Without enough fuel, your body starts breaking down muscle for energy. Muscle breakdown will make it harder for you to stay active and perform daily tasks.

You may also lack essential vitamins and minerals, like iron, calcium, and vitamin D. These nutrients are vital for a strong immune system, sustaining energy and preserving bone density. Nutritional deficiencies can lead to brittle hair and nails and weak bones.

Undereating might mean you’re not getting enough protein. Protein is crucial for maintaining muscle mass. It also helps manage satiety and cravings and allows your body to repair tissues.

Research also suggests that prolonged undereating and muscle loss can slow your metabolism. This can make it difficult to achieve sustainable, long-term weight loss.

Signs of Undereating

If you’re regularly eating less than your body needs, the signs will start to present themselves both physically and mentally.

The main sign of undereating is losing too much weight. On Mounjaro, you should be aiming for steady weight loss of 1-2lbs pounds per week. You might lose more weight at the beginning of your journey (because you’re losing water weight). But consistently losing more than that might be a sign of undereating.

Here are some other common signs that you might be undereating:

  • Fatigue: You may feel tired throughout the day, as your body lacks the fuel it needs to run as well as normal.
  • Frequent Illness. Similarly to fatigue, your immune system will not work as efficiently without sufficient fuel. So you might get ill more often.
  • Hair Loss: In order to build new hair, your body requires nutrients – eating less will leave you without the appropriate nutrients, leading to hair follicles dying off.
  • Sexual Health Issues: While tiredness can contribute towards erectile dysfunction, amenorrhea (lack of menstrual period) is also a common issue facing people who don’t eat enough.
  • Feeling Cold: Much like a fire without fuel, your body cannot control your temperature as easily without energy.
  • Skin Conditions: Vitamin E and other nutrients are essential for skin health. By depriving your body of these essentials, you may find your skin is more easily damaged.
  • Depression: Some studies have linked depression with malnutrition. However, depression is a complex condition, and may be part of a wider set of issues.
  • Constipation: With less food to process, your bowel can slow the passage of faeces, leading to constipation.

The Importance of Balancing Weight Loss With Nutritional Needs

If you’re using Mounjaro, you will feel less hungry than before you started your journey, which means you’ll be eating less food. But it is still important you’re fuelling yourself correctly. That means eating enough.

It might sound counterintuitive, but eating enough nutrient-dense food will help you lose weight steadily – and keep it off. It will help you maintain muscle mass, keep your hormones balanced and aid digestion.

Feeling better, stronger and more energised, you’ll be more likely to stick to your healthy lifestyle in the long-run.

Your body needs three essential types of nutrients: carbohydrates, proteins, and fats. Each plays a vital role in maintaining your overall health, especially when you’re focusing on weight management. Proteins and fats are used quickly by your body for energy, while carbohydrates serve as a crucial source of fuel that can be stored for later use.

By finding the right balance, you can enjoy the benefits of all three nutrient types and feel good about your food choices.

Tips For Eating Enough on Mounjaro

Eating enough food on Mounjaro doesn’t need to be a chore. With a few key changes to your eating habits, you can ensure you are getting enough to eat even while you feel less hungry.

Eat Regular Meals

Sticking to three meals a day is the best way to make sure you manage to eat enough. We recommend setting specific meal times to make sure that you are still eating even when you feel less hungry.

Eat breakfast, lunch and dinner at roughly the same time each day. This will allow your body to get used to your new diet, and should allow your body to know when you need to eat.

You can also include snacks. A lot of patients find eating little and often easier than eating three big meals a day. It can also ease side effects like nausea and constipation.

Drink Enough Water

Make sure you’re drinking enough water throughout the day as it will help you regulate bowels – as well as help you manage side effects like headaches.

Focus on Nutrient Dense Foods

Build each meal around key macronutrients: proteins, carbohydrates, and fibre.

Incorporating high-quality proteins like fish, chicken, and legumes will help support muscle health and keep you satisfied.

Opt for healthy carbohydrates such as whole grains and fruits, which provide energy and essential vitamins. It’s important to understand that carbohydrates are not the enemy; they are a key part of a balanced diet.

Don’t forget to include plenty of vegetables in your meals. They are a fantastic source of fibre and nutrients that support overall well-being. 

By ensuring that each meal contains a balance of these important building blocks, you can fuel your body effectively. Over time, this will help promote a healthy, sustainable way of eating that makes you feel good. Prioritise the quality of your food choices, and enjoy the process of creating nourishing meals that you love.

Set a Minimum Calorie Goal

If you think you’re eating too little, it might be worth looking at the amount of calories you’re eating on a typical day.

A minimum goal will depend on how many calories you normally eat. But the NHS recommended calorie levels for weight loss are 1,900 per day for men, and 1,400 per day for women.

However, it is important to note that calories are not the be-all and end-all of weight loss. Counting calories as a method of losing weight might mean you prioritise low-calorie foods over nutrient-dense options.

Getting the right nutrition and eating foods you like are always more important to forming a lasting diet plan. So focus on nourishing your body with essential nutrients rather than worrying about specific calorie counts.

Calorie-counting can also lead to obsession and disordered eating. So if you think you’re susceptible to this way of thinking, setting calorie goals might not be suitable for you. It’s also important to tell your healthcare provider about your attitude toward food and eating.

Plan and Track Your Meals

Making sure you have something nutritious and healthy ready to eat is the key to maintaining a healthy diet. This means you’ll be less likely to reach for fast food (which can be full of “empty calories”).

Planning your meals, meal prepping and having snacks ready will make it easy to grab something nutritious to eat. This will help make sure you’re eating enough of the right foods.

Check out our series of blog posts to help you plan your meals while using Mounjaro:

Should I Eat When I’m Not Hungry?

It is important to make sure you are still eating, so you’re fueling your body as you lose weight. So, yes. This might mean eating when you’re not hungry.

When to Seek Support

It’s important that you still feel some hunger when you’re using Mounjaro, although you won’t feel as hungry as before you started treatment.

So, if you feel that you are not hungry enough to eat, or your side effects make eating difficult, speak to your doctor or one of our pharmacists. They’ll discuss your current dosage and make any changes if it’s not right for you.

A healthcare professional or dietician can also help you if you’re worried about undereating. They’ll be able to assess your diet and advise you on changes you can make to your diet. You should also seek medical help if you’re displaying any of the signs of undereating outlined above.

If you have any questions or concerns about diet or dosage, we’re here to support you at every step. Call us on 0141 774 5023.

You can also download our Renu app for additional support. You’ll get access to tailored support from our clinical team, with plenty of resources on food, movement and mindset.

Get tailored weight loss advice with our Renu app

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Key Takeaways

  • Undereating Harms Health and Slows Weight Loss: Eating too little can lead to muscle loss, nutrient deficiencies, and a slower metabolism. This can also make it harder to sustain weight loss long-term.

  • Common Signs of Undereating: Extreme fatigue, frequent illness, hair loss, feeling constantly cold, digestive issues, losing more than 1-2 lbs per week and mood changes can indicate you’re not eating enough. 

  • Eat Nutrient-Dense Foods: Prioritise protein, healthy fats, and essential vitamins and minerals. This will help maintain muscle mass, balance hormones, and keep energy levels stable – key for long-term weight management.

  • Meal Planning and Eat Regularly: Stick to set meal times, incorporate snacks, and meal prep. This can help you eat enough of the right foods.

  • Seek Help If You’re Struggling: If appetite suppression becomes too extreme or side effects make eating difficult, speak with a healthcare professional to adjust your dosage or get tailored nutritional advice.

References

Fick, M. (2024). Lilly’s Mounjaro more popular than Wegovy in UK’s private obesity drug market. Reuters. [online] 13 Dec. Available at: https://www.reuters.com/business/healthcare-pharmaceuticals/lillys-mounjaro-more-popular-than-wegovy-uks-private-obesity-drug-market-2024-12-13/.

‌Fuller, N. (2024). 3 signs your diet is causing too much muscle loss – and what to do about it. [online] The Conversation. Available at: https://theconversation.com/3-signs-your-diet-is-causing-too-much-muscle-loss-and-what-to-do-about-it-223865.

‌Gornall, J. and Villani, R.G. (1996). Short-Term Changes in Body Composition and Metabolism with Severe Dieting and Resistance Exercise. International Journal of Sport Nutrition, 6(3), pp.285–294. doi:https://doi.org/10.1123/ijsn.6.3.285.

NHS (2020). Symptoms – Malnutrition. [online] NHS. Available at: https://www.nhs.uk/conditions/malnutrition/symptoms/.

The London Centre for Eating Disorders and Body Image. (2020). Specialist Supportive Clinical Management (SSCM) for Anorexia. [online] Available at: https://www.thelondoncentre.co.uk/treatment-read-more/effects-of-starvation.

Golding, J., Steer, C., Emmett, P., Davis, J.M. and Hibbeln, J.R. (2009). High Levels of Depressive Symptoms in Pregnancy With Low Omega-3 Fatty Acid Intake From Fish. Epidemiology, 20(4), pp.598–603. doi:https://doi.org/10.1097/ede.0b013e31819d6a57.

NHS (2022). Calorie counting – Better Health. [online] nhs.uk. Available at: https://www.nhs.uk/better-health/lose-weight/calorie-counting/.

‌Harvard Health Publishing (2016). Understanding empty calories – Harvard Health. [online] Harvard Health. Available at: https://www.health.harvard.edu/staying-healthy/understanding-empty-calories.

Kandola, A. (2019). 9 signs and symptoms you’re not eating enough. [online] www.medicalnewstoday.com. Available at: https://www.medicalnewstoday.com/articles/322157.

Clinically reviewed by: Mariam Al-Hajaj, GPhC reg: 2232929

Diet advice reviewed by: Laura Perez, British Dietetic Association membership no: 24597