By MH Staff - Posted on 11th December 2013
We’ve run the numbers to help make the metabolic maths work in your favour.
Estimating the daily number of kilojoules required to keep you going is difficult even in a lab, says Hall. That’s because it’s hard to measure and it changes. Popular formulas, such as your weight multiplied by 10 (plus the number of days a week you work out) can miscalculate your kilojoule needs by at least 10%. THE COST: To show how small maths errors can carry a heavy price, we’ve cast you as this guy: you’re 35 years old, weigh 93kg, and want to drop 10kg in 20 weeks. A 10% inaccuracy would mean you’d need more than twice the time to hit 83kg. THE FIX: Hall’s team created a sophisticated online simulator, Body Weight Simulator , that factors in your age, daily activity level and exercise habits. Plugging in your stats tells us that if you have a desk job and you work out once a week, then your baseline is 12 740kJ a day. Now comes the hard part – cutting kilojoules.
Ever hear that a daily deficit of 2 090kJ would allow you to lose half a kilo a week? That’s based on wobbly 50-year-old science. It presumes you’ll lose 100% of your weight from fat and doesn’t account for your slowing metabolism, says Hall. THE COST: You might give up if this were the basis for your goal, because you would need two months longer than planned to hit your target. THE FIX: The simulator reveals that to lose 10kg in 20 weeks without additional exercise actually requires a daily deficit of 2 742kJ, which means a daily budget of 9 998kJ. When you hit your target of 83kg, you need to recalculate your baseline: your new daily max for weight maintenance is now 11 850kJ. Other research by Hall suggests that if you’re patient, you can lose five kilos painlessly. A 418-kilojoule-a-day deficit can do the trick. Half the weight will come off in a year, and 95% will be off in three years.
Even people who log every morsel bungle the maths. In a study by the Pennington Biomedical Research Center, dieters who were taught how to count kilojoules still missed 18% of them. That’s partly because restaurant menus and food labels can underestimate kilojoule counts by as much as 245%, according to research in the Journal of the American Dietetic Association. THE COST: If you lowered your intake by 1 797kJ a day, you would lose two fewer kilos in a month. THE FIX: Log smarter. Instead of counting kilojoules, give yourself a score from one to 10 for your eating habits and weigh yourself (at the same time) each day, says Alan Aragon, nutrition expert. You can give yourself one average score or record scores at, say, 11am, 5pm and 10pm. The soft spots in your diet will become obvious, and because the scale doesn’t play favourites, you’ll see if you’re maintaining a deficit or not.
The treadmill trumpets that you just zapped 3 344kJ. Don’t celebrate with that 2 926kJ-recovery shake just yet, says Scott Sehnert, a sports dietitian at Auburn University. Certain cardio machine readouts can be inaccurate – by as much as 12kJ per minute, according to a US Naval Health Research Center report. THE COST: If you overestimated your burn by 522kJ a day, you would need an extra six weeks to reach your goal. THE FIX: Use those kilojoule counts from a machine (or a tracker like the Nike+ SportWatch, R1 700, Nike retailers) to estimate how intensely you’re exercising, says Brian Zehetner, the chief science officer for Anytime Fitness. Then ignite your own adaptive thermogenesis with high-intensity intervals or circuits. You’ll burn more kilojoules in less time and can boost your after-burn – the increase in resting metabolism that Italian research shows can last for up to 22 hours.
Insufficient sleep frazzles your hormones, says Leslie Bonci, director of sports nutrition at the University of Pittsburgh Medical Center. “It stimulates hunger-inducing ghrelin and suppresses appetite-inhibiting leptin.” Sleep-deprived folks eat about 1 254 extra kilojoules a day, reports the New York Obesity Research Center. THE COST: Those 1 254kJ result in over half a kilogram lost in week one! THE FIX: Switch off bright lights and backlit electronics several hours before bed, says Dr W. Christopher Winter, a sleep medicine advisor. They interfere with production of sleep-inducing melatonin. In a study in Applied Ergonomics, people who used tablets for two hours before bed showed significant melatonin suppression. Slept poorly? Sip green tea with your morning oats. A study in the journal Appetite suggests that doing so curbs hunger and helps you eat less at your next meals. Win-win!