What Exactly is Weight Loss?
Total weight loss is made up of four things:
- Body Fat
- Muscle Mass
- Glycogen Stores
- Water Weight
It is impossible to lose just one of these, regardless of the diet you follow or the weight loss medication you take. When you lose body fat, you’ll also lose some muscle, glycogen and water. The proportion of muscle lost can increase as the rate of weight loss becomes more rapid.
For example, if you’re following a diet that puts you into a modest calorie deficit, you might lose around 0.5–1kg per week. However, someone taking weight loss medication may lose up to 3kg per week, particularly in the early stages. While this can be an excellent result, the faster rate of weight loss may also increase the amount of muscle mass lost if steps aren’t taken to preserve it through adequate protein intake and strength training.
If someone loses 20kg, that sounds fantastic. But if a significant portion of that weight comes from muscle rather than body fat, the picture becomes much more complicated and it might not be as much of a win as you might think.
How Weight Loss Medication Works
The aim of weight loss medication is to reduce appetite and food intake, helping to create a calorie deficit that leads to weight loss over time. Everyone’s experience is different, with some people experiencing only a slight reduction in appetite, while others find they have very little appetite at all. This is where the potential issues can arise.
Imagine someone who is overweight and regularly consumes over 2,500 calories per day. This is the amount of energy their body has become accustomed to using. Once they begin taking weight loss medication and their appetite is suppressed, their daily calorie intake can drop quite dramatically. As a result, their body has to adapt to functioning with much less energy.
During any calorie deficit, the body looks to its stored energy reserves to meet its needs. While much of the weight lost will come from body fat, some will also come from glycogen, water, and mainly muscle tissue. The larger and more rapid the calorie deficit, the greater the potential for muscle loss, particularly if protein intake is low and strength training isn’t part of the plan.
This is why people notice a reduction in muscle mass during a course of weight loss medication. The good news is that there are effective ways to minimise this—and one of the most important is strength training.
The Importance of Maintaining Muscle Mass
This is where strength training becomes one of your biggest tools in combating muscle loss. A well-structured strength training programme is one of the best ways to help maintain muscle mass throughout the weight loss process. Strength training provides the stimulus needed to preserve muscle. Research consistently shows that resistance training improves muscle mass, strength and physical function, making it one of the most effective tools for preserving lean tissue during periods of weight loss. In fact, an umbrella review examining 44 systematic reviews described resistance training as a “potent stimulus” for increasing skeletal muscle mass, strength and physical function[1].
Maintaining muscle mass throughout the process should be a key priority, as muscle plays a vital role in far more than just appearance. It supports strength, mobility, balance and overall physical function, making everyday activities such as climbing stairs, carrying shopping, getting up from a chair or playing with children much easier. During a period of rapid weight loss, strength training helps preserve muscle, ensuring that a greater proportion of the weight lost comes from body fat rather than lean tissue.
The benefits of maintaining muscle mass extend well beyond a weight-loss journey. As we age, we naturally begin to lose muscle mass and strength, a process that can lead to reduced mobility, an increased risk of falls and a loss of independence. Preserving and building muscle through regular strength training can help slow this decline, supporting healthy aging and improving quality of life for years to come. By prioritising muscle preservation alongside weight loss, you can not only achieve better body composition but also build a stronger, healthier and more capable body that supports you throughout everyday life and into older age.
The Role of Protein in Preserving Muscle
Alongside strength training, ensuring you’re eating enough protein is one of the most important factors in maintaining muscle mass during a weight loss journey. Protein provides the building blocks your body needs to repair and maintain muscle tissue, which becomes even more important when you’re in a calorie deficit. Due to a reduced appetite from the weight loss medication it can be difficult to consume enough protein each day. If you want to know how much protein you should be consuming, click here.
Without adequate protein, your body is more likely to break down muscle tissue to meet its needs, particularly during periods of rapid weight loss. By prioritising high-quality protein sources such as lean meats, fish, eggs and dairy products at each meal, you can help support muscle maintenance while encouraging your body to lose a greater proportion of body fat.
When combined with regular strength training, adequate protein intake gives your body the best chance of preserving lean muscle throughout your weight loss journey. Together, they help improve body composition, support recovery, maintain strength, and ensure that you’re not just becoming lighter, but stronger and healthier too.
It’s Not Just About Weight Loss
Think of this process as more than just an opportunity to lose weight—see it as a chance to build a stronger, healthier and more resilient body. Use this time to improve your fitness, build and maintain lean muscle, and lose body fat. Not only will this help you get the most from your weight loss journey, but it will also benefit your long-term health, mobility and quality of life. Your future self will thank you for it!
References
- The influence of resistance exercise training prescription variables on skeletal muscle mass, strength, and physical function in healthy adults: An umbrella review
https://pmc.ncbi.nlm.nih.gov/articles/PMC10818109/?utm_source=chatgpt.com#abs0001
