This is the holy grail question of bodybuilding! What man who lifts weights, doesn't want to lose fat and gain muscle at the same time? But the question is, is it possible?
Let's examine the facts.
The First Law of Thermodynamics
This law states that the total energy of an isolated system is constant; energy can be transformed from one form to another, but can be neither created nor destroyed.
You’ve probably heard someone say that building muscle and losing fat is physically impossible because:
The first two point are true. This law means energy cannot just disappear. It has to go somewhere. Building new fat or muscle cells requires energy and breaking them down releases energy. However, point three is false.
Muscle and fat are two totally different tissues in the body. As a results, your body directs calories towards muscle and fat independently. This is known as calorie partionining, and the change in fat and muscle mass are expressed as a P-ratio.
What do we need to build muscle tissue?
1. Lots of water (H20). Can you drink lots of water when you diet? Of course you can. Check.
2. Several kinds of amino acids which come from protein. Can you eat enough protein on a diet? Yes you can. Check.
3. Glycogen and triglycerides. This one just comes down to energy since the body can create them by itself. Muscle protein synthesis (muscle building) is an energy intensive process. So we need lots of energy.
To sum up, we need lots of water, protein, and energy. Now most people will say this energy has to come from food. This is their first mistake. You see, fat stores a lot of energy. A lb actually provides around 3500 calories worth of energy. How much fat do you have on your body right now? I suspect some, or quite a lot. Can't your body break down this body fat and provide energy to build new muscles? It certainly can. And don't forget, you'll still be getting energy from food won't you?
As long as your body has all the building blocks which it should if your training and nutrition plan is optimized, you can build muscle, and lose fat at the same time.
Real Life Examples
Theory is nice and all, but what happens in real life? Do people actually manage to build muscle while losing fat?
Overweight (26% body fat) police officers starting a weight training program lost 9.3 pounds of fat and gained 8.8 pounds of lean body mass in 12 weeks.
Ironically, it’s usually the evidence based crowd that say you can’t build muscle and lose fat at the same time. Yet people in hundreds of studies lose fat and build muscle when they start training. And that's not to mention the results I've seen from my clients as well as other gym goers who aren't in research papers. Young, old, healthy, unhealthy, male, female, obese, lean, they all achieve body recomposition (build muscle/lose fat).
Even on crappy training programs with crappy diets with suboptimal protein intakes. Even elderly men and women over 60 years old generally gain around 4 pounds of lean body mass with the same amount of fat loss in 12 to 16 weeks (see here and here, for example).
Still not convinced? In trained individuals it doesn't happen as often like in beginners, but it’s still possible if you’re on a good program. Many of my clients have gained muscle while losing fat.
See, below for 3 examples.
And here are some more examples from studies:
Gaining muscle and losing fat is not only possible, it should be expected for most people on a serious program. As long as the program is optimized towards muscle growth, you will build muscle and lose fat.