Let’s start with some biochemistry and look at what is actually happening when we create lactate during training.
What is lactate?
Without getting too deep into biochemistry, the (very) simplified version is that lactate is a byproduct of muscular contractions when there is insufficient oxygen for the mitochondria in your cells. Note that this means that not all muscular contractions will result in lactate production, which is why workout design is important if your goal is to achieve lactate production and accumulation.
Lactate is not just a waste product from muscular contractions that has no further use though. In fact, it can be recycled by the liver through a process called the Cori cycle.
The liver converts the lactate back into glucose which can then be used by the working muscles as fuel for further contractions. Cool right?
You might be wondering how this is relevant to fat loss.
Well, turning lactate into glucose in the liver is an energy negative process. It actually costs a net of 4 ATP (your body’s energy currency) to convert the lactate back to glucose.
So not only are you using up ATP with each muscular contraction, but you’re using it to recycle the lactate to fuel more contractions. The more lactate you create, the harder your liver will be required to work and the more energy it will burn through. This means you can burn more calories than just what is required to fuel your working muscles with a workout that also increases lactate production.
That is just one benefit of lactic training for improving body composition.