Why zero-calorie sweeteners don’t deliver weight loss benefits in population studies.
What the evidence says
- Epidemiological studies show frequent artificial sweetener consumers at increased risk of weight gain, metabolic syndrome, type 2 diabetes[1]
- San Antonio Heart Study (7–8 year follow-up): adjusted BMI change was 47% greater among artificial-sweetener users than non-users — which in absolute terms is +1.48 against +1.01 kg/m², a difference of about half a BMI point over seven or eight years (P < 0.0001)[2]
- Dose-response relationship: heavy consumption (>21/week) almost doubled obesity risk (OR = 1.93)[2]
- A single sucralose dose before a glucose load decreased the insulin sensitivity index by 23 ± 20% (P < 0.01) and raised peak insulin secretion rate by 22 ± 7% (P < 0.02) — in 17 obese adults (15 women), insulin-sensitive at baseline, who did not normally use non-nutritive sweeteners. Note the error on the sensitivity figure: ±20 on an effect of 23 is nearly as large as the effect itself[3]
- Risk persists in participants who were normal weight at baseline, arguing against pure reverse causation (people gaining weight switching to diet drinks)[1]
- The authors of the cohort study put their own conclusion as a question: ”these findings raise the question whether AS use might be fueling — rather than fighting — our escalating obesity epidemic.” Raising a question is what an adjusted observational association can do[2],[1]