Fat loss tips that are PROVEN to work. Trust us, we asked the scientists.
“We accumulate stored fat very fast,” says Dr Pablo Enriori, from Monash University’s Neurophysiology research group. “In 15 minutes you’re going to get a lot of insulin in circulation. This is induced to accumulate fat in tissue as well as used in the form of glucose for muscles.”
“Six hours is when we start to store that body fat but if by lunch you’ve overeaten and starting to store fat you’ve still got half a day to fix it, by either going to the gym and burning it off or reducing the amount of food you’re eating later in the day,” says exercise physiologist and dietitian Matt O’Neil from Metabolic Jumpstart.
“By the next day you’ll have more body fat unless you have burnt it off the same day.”
So how to release it? Pay attention – it’s tricky.
CHEAT: Aerobic exercise needs to performed for 30 minutes plus.
DEETS: Fat is like the money in a high-interest linked savings account – you can’t just withdraw it. First you need to use up what’s in your direct transaction account (preferred macromolecules) – starting with creatine phosphate and glycogen.These provide quick energy for short-term, high-intensity exercise, or fuel for the early stages of moderate-intensity workouts.
The type and duration of exercise determines which macromolecule is metabolised first.
Why is half-an-hour the magic number?
When you keep busting a sweat past the halfa mark, the body switches from primarily metabolising glucose to favouring fatty acids. In plain speak, that means it can efficiently tap into free fatty acids (FFAs) derived from lipids in body fat. Tip: the brain can’t metabolise fatty acids during the first 30 minutes of exercise.
There’s also an order of events that can’t be overwritten, no matter how clever you think you are. Fat and amino acids derived from muscle protein are the last fuel in the chain after stored glycogen and residual glucose in blood.
The takeaway is that sub-30 minute aerobic exercise can prevent new fat stores but not erode the old ones (and possibly decrease muscle mass – bad). To really reap the perks of a fat-burning workout, 40 minutes is the holy grail. Then the body feasts primarily on fatty acids for fuel, reducing body fat. Bonus: since most fuel is now FFAs, muscle protein is largely spared.
CHEAT: Do weights before HIIT or cardio
DEETS: There’s a good reason to do weights first, cardio second – and not just because exhausting yourself in sprints will undermine your strength.
Weights use creatine phosphate and glucose sequentially for fuel while in high-intensity anaerobic exercise, the body initially uses up all of the glycogen in the skeletal muscle and the liver through the glycolysis pathway.
Once it’s worked through this, and its glycogen-derived glucose, it relies on liver breakdown of proteins and lipolysis for energy. Doing aerobic exercise first exhausts creatine and glycogen reserves without burning much fat. The subsequent anaerobic session – weights or other – will then be bereft of reserves of energy needed for glycolysis. According to MedFitness, the best strategy for maximum fat burning is 30 minutes of weights followed by cardio, which will primarily use fatty acids for fuel.
CHEAT: Eat before a workout
DEETS: While intuitively it feels as though without a piece of toast to burn, your body will make a beeline for your fat stores, fasted morning workouts aren’t as magical as they seem.
“You’ll burn a slightly bigger percentage of fat, but do you feel energetic enough to work out sufficiently before breakfast?” asks O’Neill.
In other words, you may burn a bigger slice of the pie from fat but lose the edge when you can only reach 50 per cent intensity rather than 70. The other unfortunate flow-on is that survival mechanisms may cause you to overcompensate with subsequent meals by dialling up your hunger beyond what your body needs to function. You can wipe out a caloric deficit (the one you gave up the doona to achieve) with a single muffin.
“You’ve got a whole day to cancel out the benefits of what is really a marginal difference in fat burning,” O’Neill warns. Dr Enriori says excessive caloric deficits provoke a physiological crisis response that works against fat loss. “As soon as you start losing weight you start to lose energy expenditure.”
CHEAT: Eat back calories
DEETS: It goes against everything logic – and weight loss lore – tells us. Against advice to create a caloric deficit to lose weight, fat loss is different (for the really intricate science, see p. 58).
When it comes to liquidating lipids, there’s a delicate tipping point, where measures aimed at fat loss can actually undermine the goal. Creating too big a caloric deficit (say, eating 2,000 kilojoules below your total daily energy expenditure and knocking off another 2,000 in the gym) will, over time, predispose you to fat gain.
“If you lose weight too fast, you’re likely to lose a quarter to a third of your weight loss as muscle, and that directly compromises your metabolic rate,” O’Neill says. “If, for example, you drop 15 kilograms really fast, you could lose five kilograms of muscle – that’s the equivalent of five kilos of body fat you’re not burning up anymore.
“You should never lose more than a kg a week, with a much better target being a maximum of 0.5 kg a week, which will ensure that more of your lost weight is fat rather than muscle,” O’Neill says. Effecting a caloric deficit of about 2,000 kJ a day – or quarter of your daily intake – will enable your body to use stored fat, says dietitian Dr Alan Barclay.
CHEAT: Walk, don’t run
DEETS: When it comes to losing fat, a good old-fashioned power walk (leg-warmers optional) runs rings around running according to owner and founder of Blue Sky Health & Fitness Amanda Ferguson (blueskyfitness.com.au). NSW PT of the Year and Jetts trainer Jarrad Sullivan says power walking matches running in the fat burn stakes, with the fringe benefit of lowering injury risk (that’s reaching your goal sooner in our impatient lingo).
“Walking has just the same amount of benefits as running,” Sullivan says. In a 2007 study published in The Journal of the American Medical Association, people who walked for an hour a day shed 12 to 14 per cent of their starting weight when consuming 1,500 calories a day. The key to making walking work for fat loss is increasing the intensity (it’s not a stroll). “What you want to aim for is to increase your speed and distance over time. You’ll need to increase your heart rate and challenge yourself,” Ferguson says. The intervals so-hot-right-now in running circles are also transferable to walking.
“By adding in interval workouts and hills to your running regime you will help speed up this process. Interval workouts can be less rest, running faster or adding in hills or steps.” Powerwalking on challenging surfaces such as sand will ensure you’re still being pushed while decreasing the risk of injury. Concrete’s an ankle killer. “Aim to walk a minimum of 30 to 60 minutes per day, four to six days a week,” Sullivan says.