You can in most cases regain lost muscle mass through a process called muscle memory and through eating a healthy diet, remaining active, exercising and through getting enough protein in your diet and doing consistent strength training.
Muscle loss also known as muscle wasting or muscle atrophy is usually reversible, especially when the muscle loss was caused by injury or inactivity.
It can take a few months or so to see results of getting the muscle mass back but as long a you keep up with the exercises, strength training, staying active and eating healthy and getting enough protein you can in most cases get the lost muscle mass back.
However the older you are the longer it will often take for the muscle mass to come back and if you're in your 80s or above you might not ever get the muscle mass back but it's still good to stay active even in older age if you can.
Some reasons for losing muscle mass in your legs and arms and other areas of the body can be due to not moving around enough, not walking enough, be inactive, aging, malnutrition, not eating healthy enough and getting enough protein, certain medications and even genetics can all cause loss of muscle mass in your legs and arms and other areas of the body.
When you're not using your leg or arm muscles regularly, the body can start to break down the muscles in the legs and arms for energy which leads to muscle mass loss also known as muscle wasting or muscle atrophy.
When you don't use your muscles enough it's called physiologic atrophy or disuse atrophy.
And neurogenic atrophy occurs due to nerve problems or other diseases.
To stop losing muscle mass you should engage in regular strength training as well as eating a protein rich diet and getting plenty and adequate quality sleep.
For strengthen training to stop losing muscle mass you should do at least 2 to 3 strength training exercises a week and allow for time for adequate rest between the strength training workouts.
Also doing exercises such as lunges, push ups, rows, squats and deadlifts can also help improve muscle mass and prevent and stop the loss of muscle mass.
You can also then gradually increase the weight, sets and or repetitions as you become stronger and gain more muscle mass.
Also stay consistent with the workouts to see and maintain the results in your muscle mass.
Eating a protein rich diet is important to maintain muscle mass and stop loss of muscle mass.
Protein is crucial for muscle repair and muscle growth so you should aim to get at least 1.0 to 1.3 grams of protein per kilogram of your body weight.
This is especially true when you're actively engaging in strength training.
To get enough protein to help maintain and stop losing muscle mass you should eat lean protein foods in your diet such as fish, chicken, beans, eggs, lentils and dairy products.
Sleep is also very important to stop loss of muscle mass and maintain your muscle mass and sleep also helps the body recover and rebuild muscle tissue and keep you healthy overall.
You should try to get 7 to 9 hours of sleep and quality sleep per night and practice good sleep hygiene like maintaining a regular sleep schedule, creating a relaxing bedtime routine and also ensuring you have a comfortable sleep environment.
Also ensure that you're getting enough calories to support your activity level and muscle building goals and drink plenty of water to keep hydrated and support muscle function.