A recent study by researchers at the University of Virginia found that high-intensity exercise training disposed of more belly fat in obese middle-aged women than lower-intensity training of the same energy expenditure.
The idea that doing high-intensity interval training burns off stubborn fat and visceral belly fat has been around for quite a few years. The premise has always lacked strong evidence in my opinion — or at least reasonable qualification. Any number of internet training and fat-loss gurus are promoting this idea.
What is High-Intensity Training?
First up, we need to get the concept straight. What exactly is the ‘interval training’ or ‘high-intensity training’ or ‘high-intensity interval training (HIIT)’ that we hear so much about?
Interval training is intermittent training, often near your maximum, in which you do a lap of an oval, or a spin on a bike, or 60 seconds on a treadmill very fast, then you recover, and do it again several times. That’s simple enough.
For example, I’m a masters sprinter and in training I might do 10 x 100 metres at 95% capacity, or 10 x 40 metres at 100% capacity. This is high-intensity interval training in real life. But I’ve been a marathoner and triathlete as well (don’t ask), and high-intensity training for those disciplines is mostly entirely different; say, 2km fast, 2km slow, 2km fast; or 6 x 400 metres at 90% capacity, or even, I might add, 5km at race pace, which is still high-intensity training, even if not interval training. And further, I know that if you run 40 to 60 miles a week in marathon or triathlon training you’ll burn fat . . . lots of it. So what’s this HIT stuff all about?
Early Investigations Were Not Adequate
One problem with some of the earlier studies was that they did not set a rule for what constitutes ‘high intensity’. The study I quoted above used lactate threshold to determine this, an excellent idea. And few earlier studies actually compared the different intensities for the same energy expenditure, which is what needs to be done to get a reasonable comparison.
You can’t just do 6 spins on a stationary bike for 30 seconds flat out and expect to burn the same amount of calories and fat as someone who does 30 minutes on the treadmill at 85% capacity, or even a 90-minute run at slow pace for that matter. Energy expenditure, which just about always includes some fat and glucose burning, is going to be a product of intensity X time for any physical activity.
In that event, the best approach for fat loss and fitness goals is likely to be a combination of interval training, weight training and cardio at different intensities. Big surprise eh? No, that’s right, it’s not. It almost reflects the recent exercise guidelines issued by the US government for general health and fitness.
Persistent Abdominal Fat and How to Shed It
What the study above suggests is that high-intensity training just might be superior to to lower-intensity training, for equal energy expended, in removing belly fat, especially the visceral fat wrapped around the internal organs that has been shown to increase your risk of heart disease and type 2 diabetes. Naturally, you have to include a nutrition program with some calorie restriction as well.
Even though the study involved a small number of women, 27, it seemed to be well designed. And yet men might respond differently, as might the young or post-menopausal women. It’s an idea that has promise for designing exercise programs for the overweight and people with metabolic syndrome and diabetes and is well worth watching in the future. The main problem is one that is not going to be easily solved: that unfit, obese people are unlikely to take on high-intensity training by themselves and stick to it, despite what you see on The Biggest Loser.
Having said that, there is plenty of evidence that aerobic, cardio type programs help people lose fat in general — even some visceral fat — and aerobic exercise has additional benefits for cardiovascular protection. A combination of weights, cardio and HIT is likely to be the superior program if it can be tolerated.
The Best Type of High-Intensity Training for Obesity?
Heavy people exert quite a shock to the knees when they run long or hard. It’s a real injury concern. Running is often out of the question for obese people, let alone high-intensity running. For this reason, I favour cycle spin classes on a stationary bike. Doing this exercise in a group has advantages. The instructor will encourage hard work, but it’s possible to set your own pace by adjusting resistance and peddle cadence if you get overwhelmed. You’ll get some high-intensity work threaded with lower-intensity cardio — an excellent workout combo. A medical checkup is highly recommended for anyone moving from a sedentary lifestyle to high-intensity training.