Many nutritional falsehoods are accepted as facts, but some are more damaging than others in preventing you from getting fitter and healthier. We took a look at the science to settle any uncertainty once and for all
A nightcap helps you get to sleep
You might think that pouring yourself a wee dram after a long day sends to you sleep faster. But booze before bed isn’t the best way to get a good night’s rest because of how alcohol affects brain activity, according to research in the Alcoholism: Clinical & Experimental Research Journal. Subjects who drank just before bed had more slow wave sleep patterns – called delta activity – which is the period of deeper sleep that’s associated with restoration. So far, so good. But they also had heightened alpha wave patterns, which your brain typically displays when you are awake. The competition between alpha and delta waves disrupts sleep, which is why you’ll often wake up tired and drowsy even only after having a single drink just before bed. Horlicks, anyone?
Carbs after 6pm get stored as fat
The theory that eating carbs at night is a fast route to fat gain is built on the false assumption that our resting metabolic rate (RMR) slows down during sleep, so any excess energy gets stored as fat. While energy expenditure does decrease 35% during early-stage sleep, according to the journal Metabolism, it then increases significantly during deeper REM sleep to the extent that RMR is the same at night as it is in the day, according to the European Journal of Clinical Nutrition. What’s more, exercise significantly increases RMR during sleep, according to the Canadian Journal of Applied Physiology, so you’ll burn more fat as your body recovers. In reality a high-carb dinner can help reduce body-fat levels by sending you to sleep faster because carb consumption increases blood concentrations of tryptophan, an amino acid that makes you feel drowsy. Subjects fed a high-carb dinner in the four hours before bed fell asleep faster than those who weren’t given carbs, according to research from the University of Sydney.
Margarine is better than butter
Butter was cast into the nutritional wilderness for decades because of the perceived link between its high saturated fat content and heart disease, obesity and high cholesterol. But support for butter is spreading – sales are up 7% globally in the last five years as margarine sales fell 6%, according to research firm Kantar Worldpanel – because the data behind these claims has been largely discredited. A meta-analysis of 72 studies of 600,000 people from 17 countries, published in the Annals of Internal Medicine, found total saturated fat has no association with heart disease, while research in the British Medical Journal found rates of death among men with heart disease actually increased when they ditched saturated fat for the type of polyunsaturated fat found in margarine. Butter is also a top source of vitamins A, D, E and K, and selenium, a powerful antioxidant that also plays a big role in an efficient metabolism. Time to dust down that butter dish.
Microwaving veg destroys vitamins
Still boiling your broccoli? Step away from the saucepan if you want to get more nutrients from the veg into your system. Researchers from Zhejiang University in China cooked broccoli using the most common cooking methods and concluded that steaming kept intact the most number of nutrients, including soluble protein, vitamin C and glucosinolate, the compound thought to be behind its cancer-fighting properties. Microwaving was next-best, with stir-frying and boiling resulting in the greatest nutrient loss because of the veg’s exposure to high heat and vitamins leaching into the water. This supports research from the Harvard Medical School that found that the best cooking method for retaining nutrients is one that “cooks quickly, heats food for the shortest amount of time, and uses as little liquid as possible”. That sounds like microwaving to us.
High-protein diets damage your kidneys
We evolved to become the smartest animal that’s ever lived thanks to a diet high in protein, so it’s hard to believe that in the last generation – a blink of the eye in evolutionary terms – it’s suddenly started damaging our kidneys. And you shouldn’t believe it because any study that links excessive protein intake to organ damage was conducted on people with pre-existing kidney disorders. If you’re in good health then a high-protein diet can increase weight loss without any damaging side-effects, according to the Journal of the International Society of Sports Nutrition, and reduce blood pressure, according to research from the Institute of Food and Nutrition in The Netherlands.