Exercise; does it make you fat?
If a fear of flab has you pounding the pavements or is driving your workouts at the gym, then a controversial new book might have bad news for you.
Can exercise make you fat? It almost seems a provocative question, so conditioned are we to believe that a good 30 to 60 minutes of training a day will eventually burn off the love handles or tone up thunder thighs.
Now science expert Gary Taubes is turning the food pyramid on its head and questioning the long-held beliefs that exercise will make you thin and counting calories will keep you lean.
In his book, Good Calories, Bad Calories, which is currently sparking divisive debates in the US, Taubes argues that after seven years of research he's found that almost everything we believe about the nature of a healthy diet is wrong. and that exercise may just make you reach for the hot buttered toast rather than help you slim down.
"The one thing that might be said with certainty about exercise is that it tends to make us hungry. Maybe not immediately, but eventually," Taubes says.
"Burn more calories and the odds are very good that we'll consume more as well. And this simple fact alone might explain both the scientific evidence and a nation's worth of sorely disappointing anecdotal experience."
Taubes' concentration on avoiding certain carbohydrates, and worrying less about sweating for hours a day in the gym, is actually not a new one.
As far back as 1863 he says "physicians would routinely advise their fat patients to avoid carbohydrates, particularly sweets, starches, and refined carbohydrates".
That practice continued until the 1960s, when the American Heart Foundation started recommending fat-restricted, carbohydrate-rich diets to combat heart disease. It was later applied to combating obesity, and the idea of restricting carbohydrates was sidelined.
Similarly, prior to the 1960s, Taubes says no one thought that exercise would make you slim. Russell Wilder, an obesity and diabetes expert at the Mayo Clinic in the 1930s, said his fat patients lost more weight after resting in bed.
Physicians of the time, Louis Newburgh and Hugo Rony, concluded likewise in the 1940s that for the amount burned with exercise it was hardly worth the effort.
Our reasons for thinking differently, Taubes says, came courtesy of one Jean Mayer, a physiological chemist from Yale University, who in the 1950s, after only a few months of laboratory rat experiments, started singing the praises of exercise in weight control.
His theories caught on and by the end of the decade he was credited with destroying the myth that exercise played little role in weight control.
Taubes' resurrection of such pre-1960s claims about exercise are unlikely to win favour among gym owners or sportswear companies who have profited hugely from our ever-expanding waistlines. But Taubes is not throwing out the notion of health and fitness entirely; just that it may not be the most effective tool in fighting fat.
"In Ireland alone, recent data indicates that one in five Irish children is overweight. ... The explanation given to this Western phenomenon for the last five decades was a very simple, people were obese because they ate too much and didn't exercise.
The truth is more complex, Taubes argues: the problem lies in refined carbohydrates and sugars and the effect they have on insulin, which regulates fat accumulation. The kinds of calories we consume are more important than the number."
Another factor never explained was why some people were just fat no matter how much exercise they undertook, while others remained thin as whippets.
"They are people whose bodies are programmed to send the calories they consume to the muscles to be burned, rather than to the fat tissue to be stored," Taubes claims.
"The rest of us tend to go the other way, shunting off calories to fat tissue where they accumulate to excess."