When most obesity researchers look at a plate of food, they see macronutrients – carbs, proteins and fats. Not Dr Randy Seeley, a professor of endocrinology at the University of Cincinnati and the director of the Cincinnati Diabetes and Obesity Centre. Seeley sees something else: cocktails of hormones.
Food is more than just kilojoules, Seeley says. "It can also act like hormones, activating genetic switches that trigger body-wide reactions." These reactions, in turn, can lead to metabolic upshifts and downshifts that affect fat burning and fat storage. Seeley's recent article in the journal Science details some of these cascading effects, which can be set off by specific amino acids, fats and fibre. The important question, he says, is this: "What are different foods doing inside our bodies – aside from providing energy – that make a kilojoule deficit produce or not produce weight loss like we expect?"
As an example of the hormone-like power of food, he points to omega 3s. "They are anti-inflammatory because they activate a cellular receptor called GPR120." Reduced GPR120 signalling is associated with inflammation, weight gain and impaired blood-sugar control, he says. It's another reason – along with the heart and brain benefits – to eat cold-water fish, such as salmon, twice a week or take a daily omega 3 supplement. Scientists don't have all the genetic responses to different foods mapped out, but that's no reason to wait. It's time to start hacking your metabolism. You'll drop more kilos and keep them off – for good.
Make Protein Your Entry
Protein is well known for its muscle-building role, but its greatest benefit may lie in its impact on the hormones that regulate weight loss. In a study in the journal Nutrition & Metabolism, people who consumed a 10-gram whey protein shake before breakfast and dinner over 12 weeks shed more fat than those who drank a control beverage with similar kilojoules but less protein. And not just a little lard: they lost 73 per cent more fat. How's that work? The premeal hit of protein moves the dial on the hormones that affect fullness before you even start eating. Plus, the extra essential amino acids ensure that protein synthesis is maximised at each meal. This helps you retain muscle – which burns more kilojoules than fat – thereby aiding weight loss.
Try It: each day, mix 10g of whey protein isolate in water and drink it before two meals.
Have Fun With Biochemistry
Scientists can't yet prescribe a diet based on your DNA, but they do know enough to help you match your food choices to your biochemistry. This could mean the difference between a 1.5kg and a 6kg loss over six months. In a recent study from Stanford University School of Medicine, researcher Dr Arianna McClain found that people with insulin resistance (an impaired ability to process carbohydrates) couldn't stick to a high-carb, low-fat diet as well as they adhered to a very-low-carb diet. "At some level, there is a physiological disconnect in people who are insulin resistant to the high-carb, low-fat diets," says McClain. "They just stopped following the diet." And sticking to a diet is the crucial factor in weight-loss success.
Try It: ask your GP about having your lipid profile tested. If the ratio of your triglycerides to your HDL (good) cholesterol is greater than three (a surrogate marker of insulin resistance), then place a greater emphasis on restricting carbs and eating more protein and fat. If the ratio is less than three, then feel free to eat more carbs and less fat, as long as you're meeting your weight-loss goals.
Build Muscle While You Sleep
Common lore is that eating late at night makes you fat. Wrong, says Dr Luc van Loon, a professor of exercise physiology at Maastricht University in the Netherlands. His research shows that protein digestion and absorption function properly even during sleep. In one study in Medicine & Science in Sports & Exercise, van Loon gave people a late-night casein-rich protein drink and observed a 22 per cent increase in their protein synthesis in the early hours, even during sleep. He also observed a more positive whole-body protein balance (indicating that your muscles have the raw materials needed for building). This suggests that sleep is actually an optimal physiological state for muscle growth.
Try It: researchers usually use casein protein, but van Loon notes that whey, casein or a combination work just as well. Scarfing down 30-40g of protein before bed optimises the benefits, ensuring that you'll wake up rested and more ripped. Try this power snack: Mix three-quarters of a cup of cottage cheese with one tablespoon of natural peanut butter and half a scoop of chocolate protein powder.
Repressing certain food urges is crucial to eating less, and you can help yourself by choosing the right carbs. In a study in the American Journal of Clinical Nutrition, Harvard Medical School researchers compared high- and low-glycaemic meals. They found that a meal with a high glycaemic index (that is, one that included refined carbs that spike blood sugar) resulted in increased bloodflow to and greater activation of your nucleus accumbens, an area of your brain responsible for cravings and reward-driven behaviour.
Try It: replace dinner rolls and white rice with low-glycaemic carbs like green vegetables, beans and high-fibre whole grains.
Time Your Carbs
Just as certain types of kilojoules can impact your belly differently, so can the time you eat certain foods. For instance, one effect of exercise is that it helps your body shuttle sugar to your muscles rather than into fat storage, says Dr Chris Mohr, founder of Mohr Results, a company that helps people hit weight-loss goals. "Imagine that your muscles are like a house with all the windows and doors locked. Glucose receptors represent the locks in your muscles," he says. "Exercise acts as keys to unlock those receptors."
Try It: eat most of the carbs in your diet in the hours following exercise, says Mohr. On days that you don't work out, even a 10-minute walk can help you process carbs more efficiently.
Curate Your Gut Bacteria
You know how people who quit smoking tend to gain weight? A study by the Swiss National Science Foundation found one likely reason: a change in their gut bacteria. Your digestive tract is home to more than 100 trillion microorganisms, mostly bacteria, that can influence your metabolic rate. The more good bacteria that you can nurture, the more you crowd out the bad ones. There are two ways to promote the good guys: first, you can consume probiotics, beneficial bacteria found in yoghurt, certain kinds of cottage cheese, sauerkraut, kimchi and kefir.
Second, you can eat prebiotics – specific fibres that good bacteria in your colon feast on. Naturally occurring in Jerusalem artichokes, leeks, legumes, onion and garlic, these fibres are also becoming common additions to yoghurts and protein bars. When good bacteria break them down, a variety of compounds are produced, one of which is acetate, a short-chain fatty acid. It activates cell-surface receptors in your intestines, which eventually results in a greater release of a fat-burning, appetite-squashing hormone called leptin.
Try It: aim for 5-10g of prebiotic fibre a day from the whole foods mentioned above and from processed foods containing prebiotic fibre. Look on labels for inulin and isomalto-oligosaccharides; Quest protein bars are a good choice. Also eat one daily serving of a fermented food, such as a glass of kefir or a cup of yoghurt.