If you haven’t heard of brown fat, here’s your primer: unlike the white fat that jiggles when you do burpees, the brown stuff is firm and metabolically active. Fifty grams of brown fat burns about 1250 kilojoules a day. And as it turns out, a hormone exists that can turn your white fat brown. It’s called irisin. Its existence in humans was confirmed only recently, says Dr Christiane Wrann, of the Boston-based Dana-Farber Cancer Institute. If you can get your veins to course with irisin, you might be able to eliminate that burpee jiggle.
FREEZE YOUR ARSE OFF
Shivering for 10-15 minutes increases your irisin production about as much as an hour of moderate exercise does, according to research from the US National Institutes of Health. If you’re not willing to freeze then keep your biggest muscles – the ones in your legs – contracting, says Wrann. Running and cycling will do the trick.
Related: Get On Your Bike
Ghrelin and Leptin
These two characters are constantly fighting to tell you how much food you need to eat. Ghrelin, which makes you feel hungry, is secreted by the stomach walls. Leptin, released from fat cells, tells your body that your energy stores are full.
Once in your bloodstream, both hormones flow towards your brain’s hypothalamus. In healthy men, the one that shows up in the greatest numbers wins. But when you stop taking care of yourself, your body becomes resistant to leptin. The result: ghrelin – the hunger-causing hormone – starts winning the battles.
According to researchers at Pennsylvania State University, people who sleep fewer than six hours a night see appetite-inducing ghrelin levels surge while leptin declines. And no, sleeping in at the weekend doesn’t compensate for the damage. If you want a flat belly, you need plenty of shut-eye every night.
The thyroid, a bat-shaped gland in your neck, churns out the hormones T3 and T4, which travel through your body, telling each cell how much energy to produce and expend. That determines your basal metabolic rate – how many kilojoules you burn before factoring in daily activities and exercise, says Dr Steven Lamm, of New York University’s Tisch Centre for Men’s Health. Even small dips in T3 and T4 can cause your metabolism to stall and the kilos to mount. If the dip is sudden, it could be due to a tumour or autoimmune condition, such as Hashimoto’s disease.
DINE ON IODINE
If your body weight spikes, see your doctor, says Lamm. A simple blood test can determine whether you have a thyroid disorder. Otherwise, keep the gland healthy by consuming about 150 micrograms of dietary iodine a day. The mineral is essential for your body’s T3 and T4 production. Saltwater seafood, dairy and eggs are all good sources.
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