Is sugar really that bad for you?

The World Health Organization (WHO) recommends keeping free sugars – added sugar plus the sugar in honey, syrups and fruit juice – below 10 percent of daily energy, with a conditional suggestion of below 5 percent. The recommendation rests on effects on body weight and dental health, not on any claim that sugar is toxic.

A systematic review in the BMJ (Te Morenga and colleagues) pooled 30 controlled trials and 38 cohort studies. The picture was consistent: when people cut their sugar intake, body weight fell by around 0.8 kg, and when they raised it, weight rose by about the same amount. But when sugar was swapped for the same number of calories from other carbohydrates, nothing happened to weight. In other words, sugar acts through calories, not through some fat-driving property of its own. Sugar-sweetened drinks stand out: those with the highest intake had a clearly higher risk of becoming overweight, likely because liquid calories are easy to drink without feeling full.

And "sugar like cocaine"? A review in the European Journal of Nutrition found little support for sugar addiction in humans. The addiction-like behaviour seen in rats appears only under intermittent access and is driven by sweetness and palatability, not by a chemical hook in the sugar itself.

A complicated calorie message sells worse than a villain. "Sugar is poison" and "sugar like cocaine" make headlines, book titles and an enemy to point at, and a large market profits from that enemy. Sugar-free products, detox programmes and supplements all position themselves against the one ingredient everyone has been taught to fear. Animal studies of rats bingeing on sugar get cited widely, while the caveat – that it only happens under scheduled access – drops out along the way. What remains is a simple story that feels true but that the research does not support: that a single gram decides, rather than the whole diet.

You don't need to eliminate sugar to succeed. What decides your weight is your total energy over time, and a little sugar fits comfortably within it. Keep an eye on sweetened drinks – soda, juice and energy drinks add calories without filling you up and are easy to overconsume. Look after your teeth regardless of weight. If you want to see how carbohydrates and sugar fit into your daily budget, work out your macros.