The World Health Organisation suggests that adults should eat no more than 50 grams of sugar (12 teaspoons) per day to avoid the risks of obesity and tooth decay.The UN body even advises that limiting ourselves to 25 grams – or 5% of our daily energy intake – would provide “additional health benefits.”.hat’s 2.8 grams of sugar per slice. If, for example, for breakfast you have two slices of white bread toast with chocolate spread, a 20cl glass of supermarket orange juice and a hot chocolate, you have already consumed around 63 grams of sugar, 13 grams more than what the WHO recommends for the entire day.