How much sugar is too much?
Getting more than 10% of your daily calories from free sugars, roughly 50 grams, increases the risk of metabolic syndrome, type 2 diabetes and cardiovascular disease. Sugar-sweetened beverages are the easiest place to start cutting back.
International guidelines draw the line for free sugars at 10% of daily energy intake. For an average adult, that works out to roughly 50 grams per day. People who consistently eat more than this have a higher risk of metabolic syndrome: a combination of excess belly fat, high blood pressure, disrupted blood sugar and poor blood lipids. Metabolic syndrome in turn doubles the risk of cardiovascular disease and increases the risk of premature death by half.
Sugar-sweetened beverages, such as soft drinks and fruit juices with added sugar, are the main culprit. A large Australian cohort study of more than 36,000 people showed that drinking such beverages daily is associated with a 23% greater chance of developing type 2 diabetes compared with drinking them rarely or never. Notably, once researchers adjusted for body weight, this association disappeared. That suggests excess weight is the most important intermediate step, though a direct effect of sugar itself cannot be fully ruled out on that basis.
A broad analysis of multiple studies confirms the pattern, but tempers the certainty. That analysis estimates the increased risk of type 2 diabetes from regularly drinking sugary beverages at a minimum of 8%. The risk of a blocked coronary artery was at least 2% higher. The researchers themselves emphasise that the evidence for these associations is still moderate or inconsistent, and that further research remains necessary.
Cutting back on sugar also helps with acid reflux. In a smaller randomised study of 98 people with reflux complaints, an average reduction of 62 grams of sugar per day led to measurably less acid exposure in the oesophagus and less trouble from heartburn and sleep problems. This is one of the more concrete indications that reducing sugar has measurable benefits beyond weight and blood sugar.
Energy drinks deserve a separate mention. Sugar-rich energy drinks can adversely affect blood sugar and insulin levels and lead to weight gain if the extra calories are not accounted for within your total daily intake. For children under 12 and pregnant women, they are discouraged in any case.
Based on a narrative review, a large Australian cohort study (n>36,000), a Burden of Proof meta-regression, an RCT in 98 veterans, and a position statement from the ISSN. None of the human studies demonstrate direct causality; the strongest evidence is for metabolic syndrome and the 10% sugar threshold.