We are in serious danger of missing the bigger picture when it comes to the fat versus sugar debate. “Fat makes you fat” is a half-truth. Yes, too much fat makes you fat. But excess carbohydrate makes you fat too. And excess protein is also converted to body fat.
There is a misconception that the more protein the better. But what you don’t burn in activity or need for muscle development, you store as fat.
“Sugar gives you energy” is another half-truth. Yes, one gram of sugar gives you 4kcal. But one gram of protein will yield similar energy ( 4kcal), and one gram of fat 9kcal. The bottom line is an excess of calories above your body’s needs, irrespective of where those calories come from, will make you fat over time.
Energy balance is critical when we deliberate the current obesity pandemic. However, we also need to think of nutrient balance too. Many popular diets like Atkins and Dukan blame carbohydrate or sugar. Others like the Ornish diet insist that fat is the root of all evil. Scientists, dietetic and medical professionals worldwide are hotly debating the issues. When Dr Robert Lustig first dubbed sugar a "poison" he got our full and undivided attention. That kind of language resonates in your head when supermarket shopping.
Unfortunately, Lustig’s equally important message that it is the lack of fibre, together with the added sugar that puts children at risk, is poorly recalled. This combination of high fructose corn syrup and lack of sufficient fibre make processed foods and drinks very palatable and tempting. Fibre is found only in plant cells or carbohydrates, not in animal cells. Weight gain follows if children are sedentary, leading to a plethora of metabolic problems and fatty livers.
But our livers have the ability to metabolise some fructose and this isn’t a case for eliminating all carbohydrate-rich foods.
In 2009, the American Heart Association, together with Lustig, set a goal to decrease daily sugar consumption from an average of 22 teaspoons to six for women and nine for men. They still advocate wholegrains as part of a balanced diet.
One flawed assumption in the weight debate is that if reducing sugar or fat intake leads to weight loss, then the original weight gain must have been caused by excess sugar or fat intake. It’s like saying paracetamol cures aches so the aches must be caused by a deficiency of paracetamol.
The truth is, there is no single cause and no single treatment. Obesity is an extremely complicated disease. Lifestyle factors such as stress, what’s growing in the gut, lack of sleep, lack of exercise, as well as our food can all impact on glucose metabolism, hormonal regulation, leptin and ghrelin levels and dopamine signalling. There is any number of reasons and a range of mechanisms that lead to obesity.
And there are many different approaches you can take to lose the weight too. Scientific papers are full of contradictory findings however. Well-conducted studies about the effects of a particular approach (low fat, high protein, high fibre, Mediterranean) must be long term and involve tracking people over time, keeping them on their allocated diet. This is expensive and rare.
The literature reviews to date suggest that it does not really matter what approach you follow, it’s cutting the calories that is important for weight loss. You may lose a little more weight faster on a higher protein diet, but over the course of two years, all approaches were equally successful in promoting clinically meaningful weight loss.
The researchers noted that attendance at group sessions, satiety, hunger and satisfaction with the diet were comparable for all approaches.
In the real world saturated fat and sugar are not mutually exclusive nutrients. They occur together in many types of snack foods which we regularly indulge in (see table). One thing we should all do is examine how we snack. As you can see some snacks have both saturated and heaps of added sugar, and even more calories than your average lunch or dinner. These should be the targets for reduction.
As the saying goes “it is the dose that maketh the poison”. A small study in June 2013 found that eating processed carbohydrates can cause more hunger and stimulate areas of the brain involved in reward and cravings, leading some scientists to suggest that there may be such a thing as “sugar addicted”. Only time and research will tell.
Paula Mee is lead dietitian at Medfit Proactive Healthcare. pmee@medfit.ie Tweet @paula_mee
