You’re looking in the mirror and thinking, “Man, I’d like to be leaner.”
The folks on the talk show that you just watched said that you should be doing HIIT for fat loss. Your friend that goes to Orange Theory said the same. They mentioned something science-y like “post-exercise oxygen consumption” and how it was good for fat loss. And those Instagram trainers. They’re all talking about interval-based metabolic workouts. It seems like HIIT might be the secret you’ve been looking for.
But you’re not totally sure.
You’ve also heard people say walking is the best thing for fat loss. Or at least low and slow cardio.
What’s the truth?
Should you be doing intervals or slow and steady cardio for fat loss?
What Your Brain and Your Body Say
While you’re thinking about fat loss, the subconscious parts of your brain and your body are “thinking” about survival. Your brain evolved to find threats, discover resources, and exploit your environment to keep you alive.
So, while you’re thinking about being leaner, fitter, etc., your brain is focusing on how it needs to adapt your body to the environments, and the demands, being placed on it. That’s why we get stronger when we strength train appropriately. We give our body a dose of “threat” that it can manage. Afterwards, it adapts beyond that threat so it’s no longer threatening.
Training, then, is adapting to threats and teaching your body how to use the right energy sources at the right times to survive. No matter what type of training that you’re doing.
In the case of fat loss, we teach the body to use fat most effectively as a fuel source. The process of turning fat into fuel is called lipolysis. We make it important to the brain and body so that it adapts.
The question is, what most effectively teaches the body to use fat as fuel?
What the Research Says
A lot of folks, especially those pushing high-intensity workouts like Orange Theory, will have you believe that there is a “fat burning zone” that’s somewhere between around 70% and 90% of maximum heart rate. But research shows that isn’t true.
In a 2009 study, researchers tested the fat burning zone theory against training in the aerobic zone—between 60% and 80% of maximum heart rate. Guess what those lab coats found? Maximum fat oxidation, aka MFO, (the highest percentage of lipolysis, or using fat for fuel) happened at heart rates between 60% and 80% of heart rate maximum. Further, MFO took place at about 54% of V02max (the maximum rate of oxygen consumption).
What does that mean? It means that the subjects in the study that utilized fat the best for fuel worked at the lower, slower aerobic pace and could breathe easily while exercising.
If you want your body to learn how to use fat for fuel, lower and slower is the ticket.
As a bonus, you’ll build far more endurance by training mostly in the 60%-80% of maximum heart rate range. Even better if you stay between 60% and 70%. It’s called Zone 2.
What the Rest of the Story Says
Teaching your body to use fat as fuel is one part of getting leaner, but there are other, significant things to consider.
A big one is raising your Resting Metabolic Rate (RMR). What’s the “easiest” way to do that? Have more muscle on your frame. Strength training is an important contributor to fat loss.
NEAT is also an important consideration. It stands for Non-Exercise Activity Thermogenesis. It’s everything that we do between sleeping, exercising, and eating. That means increasing your general daily activity level is important for fat loss. (We recommend you get at least 7,000 steps in per day.)
There is also nutrition. If you’re not eating to put yourself in a slight caloric deficit, you’ll have a hard time losing fat. That means eating mostly whole foods and well-constructed meals that include proper portions of protein, carbs, and fats.
The Biggest Fat Loss Factor
…is consistency.
It’s consistently training in a way that builds muscle and teaches your body to use fat. It’s consistently eating like an adult. It’s consistently making sure that you’re getting enough sleep. So, while all of the above factors matter, including the type of conditioning you do, nothing matters if you aren’t consistent.
What the Conclusion Says
If your goal is fat loss, do most of your conditioning between 60% and 80%, with most of your efforts in Zone 2, between 60% and 70% of heart rate max. Strength train consistently, increase your daily activity level, and eat like an adult. Do all of these things consistently and you’ll lose fat and keep it off.