If there’s one golden rule of dieting, it’s this: never sacrifice your muscle mass. Why? Because muscle isn’t just for show—it’s one of the most critical factors in maintaining long-term health and longevity. For anyone embarking on a weight loss journey, the focus should always be on losing fat while preserving muscle.

Muscles are often overlooked when we talk about health. Sure, people associate them with looking fit or being strong, but muscle goes way beyond that. It is an organ of longevity. Being strong and having optimal muscle mass is imperative to long-term quality of life. Maintaining your muscles is the key to holding on to youth and independence.

Here are a few reasons why keeping our muscles as we age is essential.

Support for Daily Activities: Whether it’s lifting your kids, carrying groceries, or even just getting out of bed, muscle plays a vital role in supporting daily movements and maintaining independence as you age.

Improved Insulin Sensitivity: The muscle is like a sponge for glucose. The more muscle you have, the better your body can manage blood sugar levels, which is key to avoiding metabolic diseases like Type 2 diabetes.

Injury Prevention and Bone Health: Muscles strengthen your bones by stimulating them through resistance, reducing your risk of fractures and osteoporosis later in life.

Why I Think Muscle Loss is the Cardinal Sin of Dieting

When you go on a calorie-restricted diet without optimal nutrition or strength training, your body might burn through muscle to meet its energy needs. This is a recipe for disaster for a few reasons:

Weakening Metabolism: Muscle burns more calories at rest. Losing muscle means your metabolism slows down, which makes it harder to maintain or continue weight loss in the long run.

Higher Risk of Regaining Fat: After losing muscle, your body is less efficient at burning calories. This is why so many people regain the weight they lost after a diet—and often gain even more fat.

Declining Functional Strength & Mobility: Losing muscle doesn’t just mean you’ll struggle to lift heavier weights at the gym. Over time, muscle loss leads to a decline in functional strength and mobility, which affects your ability to perform everyday tasks and increases your risk of injury.

Negative Impact on Mental Health: Muscle loss can impact more than just your physical health. Feeling weaker and less capable can affect your confidence and overall mental well-being, leading to frustration and potentially giving up on your fitness goals.

Protecting Muscle While Dieting

How do you make sure you don’t fall into the trap of losing muscle while trying to shed fat? Here are some key strategies to focus on:

Prioritise Protein: Aim for a protein intake that supports muscle maintenance—generally around 1.6–2.2 grams per kilogram of body weight. Protein helps repair and rebuild muscle tissues, especially during a calorie deficit.

Strength Training is Non-Negotiable: Lifting weights becomes your best friend when dieting. Strength training signals to your body that it still needs its muscle, even while you’re in a calorie deficit. Aim for at least 3-4 weekly sessions, focusing on compound movements like squats, deadlifts, and presses.

Avoid Extreme Calorie Deficits: It’s tempting to cut a ton of calories to speed up weight loss, but this increases the likelihood of muscle loss. Instead, aim for a moderate deficit—about 10-20% below your maintenance level. Slow and steady wins the race here.

Incorporate Recovery: Your muscles don’t grow during the workout—they grow while you’re resting. Ensure adequate sleep and recovery, which is crucial for muscle repair and growth.

Don’t Skip Carbs and Fats: While protein is essential, carbohydrates and fats play their roles too. Carbs fuel your workouts, and healthy fats support hormone production (including testosterone, vital for muscle maintenance).

Muscle is one of the most important contributors to long-term health, mobility, and mental well-being. When dieting, make it your mission to lose fat, not muscle. Doing so will set you up for a healthier, more active, and vibrant future.