Protecting Muscle While Losing Weight with CKD

erin maurer
May 11
6 min read

Losing fat, not muscle, and using smart strategies like resistance training, regular exercise, and eating enough protein are especially important for people with conditions like chronic kidney disease (CKD), where preserving muscle can support better health outcomes. Read on to find research-backed tips and practical advice to help you lose weight in a sustainable, healthy way.

Why Muscle Matters When You're Losing Weight

Many people want to lose weight for health or appearance, but it’s important to understand that your goal should be fat loss - not muscle loss.

Muscle burns more calories than fat, even at rest. So keeping your muscle while you lose weight helps your body burn more energy and makes it easier to keep the weight off long term. Research shows that up to 25% of weight lost during dieting can come from muscle, not just fat. That’s a problem - because losing muscle slows your metabolism and makes weight regain more likely.

On top of that, muscle plays a key role in other important areas of health. It supports insulin sensitivity, bone strength, and your overall ability to move and function. So if you want long-term success, you need to lose fat while holding onto muscle.

What Happens to Muscle During Weight Loss?

When you're in a calorie deficit (eating less than you burn), your body sometimes breaks down muscle to use for energy - especially if you're not eating enough protein or not staying active.

Studies show that combining good nutrition with the right type of exercise can help prevent this. People with more body fat often have more muscle, but the quality of that muscle can be poor. And when they lose weight, some of that muscle goes, too. The key is to protect muscle while reducing fat.

Losing weight too quickly can make things worse. A 2020 study found that after extreme weight loss (like in the Minnesota Starvation Experiment), people tended to regain more fat than they originally lost - a phenomenon called "fat overshooting." This happens because the body rushes to replace lost fat faster than it rebuilds muscle. That imbalance can increase long-term fat storage and make the body less efficient.

So preserving muscle helps not just with how you look, but also with how your body recovers and functions during and after weight loss.

Core Strategies to Keep Muscle While Losing Fat

Here are some key strategies, all backed by research:

✔ Adequate Protein Intake

Protein gives your body the building blocks (amino acids) it needs to repair and maintain muscle. For most healthy people, aim for at least 1.6 grams of protein per kilogram of ideal body weight per day - about 120g for a 70 kg person. Spread your protein across meals during the day.

⚠️ If you have CKD or another chronic condition, talk to us or speak to your healthcare provider about your protein needs.

For people with CKD, we generally recommend getting between 0.8 and 1.5 grams of protein per kilogram of ideal body weight per day - about 56-105g for a 70 kg person, unless a physician recommends otherwise.

✔ Resistance Training

Strength-based exercises (like lifting weights or bodyweight workouts) are essential. Aim for 2-3 sessions per week, with rest days in between. Resistance training signals your body to hold on to muscle - even while losing weight.

✔ Endurance Activity

Brisk walking or other cardio doesn’t build muscle directly, but it supports overall health and can help with weight loss as well as mental well-being. Some studies show cardio may not prevent muscle loss on its own, but it's still beneficial when combined with strength training.

✔ Even Protein Distribution

Don't save all your protein for dinner. Try to eat roughly equal amounts at each meal - at least for two meals a day, which supports muscle maintenance better than eating most of it all at once.

FUN FACTS

Spreading your protein intake evenly across the day helps your body maintain muscle more effectively than eating most of it at once. That’s because your muscles can only use a limited amount of protein at a time for growth and repair - usually around 20-35 grams per meal.

By eating moderate amounts of protein at each meal, you give your body multiple chances to trigger muscle protein synthesis (build new muscle proteins), which supports better muscle maintenance over time. This approach is especially important during weight loss, with aging, or when managing conditions like CKD, where preserving muscle mass is necessary for health and function.

Protein is also used for other essential functions: Protein isn’t just for muscles - it’s made up of amino acids, which are important for:

➡ Building enzymes and hormones

➡ Supporting immune function

➡ Repairing tissues and organs

➡ Producing neurotransmitters for brain function

So, even if muscle protein synthesis is "maxed out," your body still uses amino acids in many other ways. If your body doesn't need the extra amino acids for repair or other functions, it may convert them to glucose (via gluconeogenesis) or use them as energy - especially if you’re in a calorie deficit or eating low carb.

Protein isn't stored like carbs or fat: Unlike carbs (stored as glycogen) or fat (stored in fat tissue), excess protein isn't stored long-term. So spread your intake across the day - to keep a steady supply for repair, recovery, and function.

Alternating Fasting and Feasting

Strategies like intermittent fasting (cycling between periods of eating and fasting) can help promote fat loss while protecting muscle. During fasting, your body becomes better at burning fat. During “feasting” periods, you support muscle repair - especially when combined with enough protein and resistance exercise.

This approach also supports metabolic flexibility (your body’s ability to switch between burning carbs and fat), and it may help reduce the metabolic slowdown often caused by chronic dieting.

Diet and Exercise: The Winning Combo

Combining a moderate calorie deficit with regular resistance training is the most effective way to lose fat while keeping muscle. You get the best of both worlds: lower body fat and a stronger, more capable body.

Choosing to follow a lower carb or ketogenic diet can make it easier to cut back on calories a little as well as to fast without experiencing energy crashes or feeling hungry all the time.

Track Your Progress with Body Measurements and Strength Levels

When you're focusing on fat loss and muscle preservation, the scale alone doesn't tell the whole story - especially with CKD, where fluid balance can shift weight unpredictably.

Regularly tracking waist circumference, strength (e.g., how many reps or how much weight you can lift), and how your clothes fit helps you see if you're maintaining muscle while losing fat. Strength gains or maintenance are good indicators that your muscle mass is being preserved, even if the scale doesn't budge.

Get Enough Sleep - Aim for 7-9 Hours per Night

Sleep is when your body repairs and builds muscle tissue - and poor sleep can increase muscle breakdown, raise inflammation, and worsen insulin resistance, which is especially problematic in CKD.

Getting quality sleep supports hormonal balance, including growth hormone and cortisol levels, both of which influence muscle health and fat metabolism. Prioritizing sleep is an underrated but powerful tool in protecting your muscle mass.

Stay Hydrated

Proper hydration helps maintain muscle function, energy levels, and kidney filtration, which is important for people with CKD. Dehydration can stress the kidneys and impair performance during exercise, making it harder to maintain physical activity - which is key for muscle preservation.

Manage Stress

Chronic stress, on the other hand, raises cortisol levels, which can increase muscle breakdown and impair recovery. Stress management techniques like breathing exercises, gentle movement, or spending time in nature can support your body’s ability to recover, repair, and stay strong.