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When trying to reach or maintain a healthy weight, you are taking important steps to improve your health and well-being. However, it is important to remember that during weight loss, you are not only losing fat, you may also be reducing your muscle, which is important for keeping your body working properly. The good news is that there are changes you can make to protect and build on existing muscle mass while on your weight management journey.
Robert Williams, living with obesity, Brazil
There are three types of muscle:
Skeletal muscle represents around 40% of your total body mass. It plays an important role in key biological processes, from storing nutrients to the stabilising joints. A lower muscle mass can affect day to day living in a number of ways, including difficulty climbing the stairs, or getting up from a chair, and an increased risk of falls and bone fractures.
Did you know that muscle mass plays a role in mobility and daily function?
That’s great! Understanding the role of muscle in supporting movement and everyday tasks is an important part of maintaining overall health and independence.
That’s completely understandable — muscle mass plays a key role in strength, balance, and the ability to carry out daily activities comfortably.
The link between obesity and reduced muscle mass is complex, with several biological processes involved. What we do know is that those living with obesity often have increased muscle mass, but the muscle quality may be lower, leading to reduced strength and power. This can have a negative impact on physical performance, particularly as you age.
During weight loss, the aim is to lose fat while preserving muscle. Multiple techniques can be used to measure whether you are reducing your fat mass, rather than muscle mass.
You may already be familiar with the Body Mass Index (BMI) calculator, as this tool is traditionally used to measuring body weight in relation to your height. However, BMI does not differentiate between fat mass and lean mass and does not take into account body fat distribution. As muscle is denser than fat, somebody with a muscular body may have a high BMI, while a lean person with a ‘normal’ BMI may actually carry a great deal of body fat. This is why a combination of tools are recommended for use alongside BMI, including Waist-to-Height ratio, and DEXA scans.
Maintaining muscle mass while losing weight may sound daunting but there are practical ways to help make it feel more manageable. Two key factors can make a significant difference: regular physical activity and prioritising protein in the diet. Together, these can increase your basal metabolic rate (BMR), which is the number of calories your body needs to function at a basic level. This means that you will burn more calories when you are at rest.
Resistance training (also known as strength or weight training) is a great way to improve muscle strength. Examples include:
There is no need to go to a gym or to buy specialist equipment to do resistance training, many activities can be carried out at home using simple household objects. For example, if you do not have weights or dumbbells, use filled water bottles or cans. Aerobic exercise, such as brisk walking, cycling, dancing or using an elliptical machine, is also important.
It is generally advised to start slowly and build up the intensity of resistance or weight activity gradually.
Increasing protein intake can help to retain and increase muscle mass in adults with overweight or obesity. Intake of more than 1.3 g/kg/day is needed to increase muscle mass. An added benefit is that protein-rich foods keep you feeling fuller for longer. Protein-rich foods should be consumed across three meals per day and includes fish, chicken, eggs, meats and cheese. Plant-based options include beans, lentils, peas (black-eyed or split), tofu and meatless meat-substitute products.
It’s important to remember that losing weight is not just about reducing the number on the scale, it’s about improving health while protecting the muscle that supports strength, mobility and long-term wellbeing. By combining regular resistance-based activity with a protein-rich, balanced eating pattern, you can better preserve (and even build) muscle as you lose fat. If you’re unsure where to start, speak to your doctor for personalised guidance and support.
