Are soda, fruit juice, and energy drinks as bad as they say?

Liquid sugar slips past your appetite. In a crossover study of 15 adults, the same extra energy eaten as jelly beans was offset by eating less of other foods, but the same energy drunk as soda was not, and weight rose only in the soda period⁷.

Soda also adds fat in the liver and belly. In a six-month trial of 47 overweight adults, 1 litre a day of regular cola raised liver, muscle and belly (visceral) fat and blood triglycerides more than milk with the same calories, diet cola or water did⁸.

Dose matters. People in the highest intake group (most often 1 to 2 servings a day) had 26% more type 2 diabetes than people who drank none or under one a month². Each extra daily serving went with 18% higher diabetes incidence, and 13% after adjusting for body fat, so the link is not only about weight⁹. Two or more servings a day went with 21% higher death risk³. "Sugar-sweetened" includes soft drinks, fruit drinks, iced tea, and energy and vitamin waters². Diet drinks are not a clean swap: artificially sweetened drinks also tracked with diabetes, though that may reflect bias⁹. See our artificial sweeteners article.

Juice is different, not harmless. It has fruit's sugar without most of its fibre or protein, which can promote excess weight gain and tooth decay in children¹². In large US cohorts, each three servings a week of fruit juice went with 8% higher diabetes risk, while blueberries, grapes and apples went with lower risk⁴. Yet a review of 15 systematic reviews found about three quarters of outcomes unchanged and some, such as blood pressure, improved, and concluded the evidence does not justify excluding 100% juice from healthy-eating guides¹⁰.

Energy drinks frequently contain high, unregulated amounts of caffeine alongside sugar and understudied ingredients, and 30% to 50% of adolescents and young adults report using them¹¹. In a trial of 34 healthy adults, 32 oz within an hour lengthened the corrected QT interval and raised blood pressure compared with placebo⁶.

What to do. Water, sparkling water and plain tea or coffee are the easy default. Check labels for added sugars, and for the wider picture see our added sugar guide.

Weight

A meta-analysis of 85 articles pooled cohorts and trials in children (40 cohorts, 91,713 children; 8 trials, 2,783) and adults (21 cohorts, 448,661; 16 trials, 1,343). In adult cohorts, each daily serving of sugary drink went with 0.42 kg more body weight (95% CI 0.26 to 0.58). In adult trials, adding sugary drinks caused weight gain (mean difference 0.83 kg, 0.47 to 1.19) and removing them caused weight loss (-0.49 kg, -0.66 to -0.32). In children, reduction programmes lowered BMI gain (-0.21 kg/m2, -0.40 to -0.01)¹. The effects are real but modest.

Diabetes and death

A meta-analysis of 11 cohort studies (310,819 people; 15,043 diabetes cases) found a 26% higher diabetes risk in the top intake group (RR 1.26, 95% CI 1.12 to 1.41) and 20% higher metabolic syndrome risk (1.20, 1.02 to 1.42)². A larger analysis of 17 cohorts (38,253 cases) found 18% higher incidence per daily serving (95% CI 9% to 28%), 13% after adjusting for adiposity, and estimated that, if causal, 8.7% of new US diabetes cases over 10 years would be attributable to sugary drinks⁹. In 37,716 men and 80,647 women followed up to 34 years (36,436 deaths), total mortality hazard ratios rose across intake groups: 1.06 for 2 to 6 servings a week, 1.14 for 1 to under 2 a day and 1.21 (1.13 to 1.28) for 2 or more a day; cardiovascular death was 31% higher at the extreme³.

Liver fat and satiety

In the 47-person trial, relative to the other three groups the cola group's change was larger by 132% to 143% for liver fat, 117% to 221% for muscle fat and 24% to 31% for visceral fat, and triglycerides were 32% higher, though total fat mass did not differ⁸. In the 15-person crossover, total daily intake rose by the full amount of the soda (compensation -17%), whereas people offset the jelly beans almost exactly (118%)⁷. Both studies were small and used large doses.

Juice

Across 66,105 women (Nurses' Health Study), 85,104 women (NHS II) and 36,173 men followed up to about 24 years (12,198 diabetes cases), every three servings a week of fruit juice carried a hazard ratio of 1.08 (1.05 to 1.11), whole fruit overall 0.98 (0.97 to 0.99), blueberries 0.74 (0.66 to 0.83) and cantaloupe 1.10 (1.02 to 1.18)⁴. A meta-analysis of 42 studies found each daily serving of 100% juice went with 0.03 higher BMI in children; in adults, cohorts that ignored total energy found 0.21 kg more weight, those that adjusted found 0.08 kg less, and 19 trials found no significant effect (-0.53 kg, -1.55 to 0.48)⁵. The umbrella review rated 10 of 51 meta-analyses as showing benefit, 3 as showing risk (cardiovascular death, prostate cancer, diabetes) and the rest no effect, with risks seen only in cohorts¹⁰.

Energy drinks

The randomised, double-masked crossover trial gave 34 healthy adults (mean age 22) 32 oz of one of two energy drinks or placebo. The maximum rise in corrected QT was 17.9 and 19.6 ms versus 11.9 ms with placebo (P = 0.005), and blood pressure was higher after both drinks (P < 0.001)⁶. A narrative review reported serious adverse effects mainly in young people with seizures, diabetes, cardiac abnormalities or mood disorders¹¹.

Where the evidence disagrees

Diabetes and mortality findings are observational, so unmeasured lifestyle differences could inflate them; the juice-diabetes link was not significant in studies that confirmed diabetes objectively⁹, and adult juice trials found no weight effect⁵. The energy drink trial used a very large volume, and QT prolongation is a surrogate, not proof of arrhythmia.

Bottom line (confidence 3 of 5). Soda is the clear problem: trials link it to weight and fat gain, and cohorts to diabetes and mortality. Juice is a small, mixed signal best treated as a sweet occasional drink. Energy drinks are a stimulant risk for young people and anyone with heart conditions.