Research paper
Hall KD, Sacks G, Chandramohan D, Chow CC, Wang YC, Gortmaker SL, Swinburn BA. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011 Aug 27;378(9793):826-837. doi:10.1016/S0140-6736(11)60812-X
Why we cite it
Provides ”a validated web-based dynamic simulation model of adult human metabolism” for predicting weight change over time, against the static “3500 kcal = 1 pound” rule, which ”ignores dynamic physiological adaptations to altered body weight” (corrected 2026-09-10 from ”a physiologically accurate framework”, a gloss). Directly relevant to the project because it explains why weight loss decelerates (the body adapts) and provides a practical rule of thumb (10 kcal/day per pound) that sets realistic expectations for dietary change.
The paper draws a distinction this record inverted, and it is the paper’s own emphasis (corrected 2026-09-02, card E1AWST). This section previously cited the ~30 kJ/day figure as showing ”why small persistent changes matter.” Hall’s next sentence says the opposite about reversal: ”However, reversal of obesity will require substantially larger changes.”
The two gaps are different quantities and the paper names both:
– The energy imbalance gap — about 30 kJ/day — is what accumulated the weight at a population level. The paper attributes it to Hill and colleagues, not to itself, and names the ”small changes approach” it gave rise to.
– The maintenance energy gap — the increased intake needed to hold the higher weight, and therefore the size of the change needed to reverse it — is about 0.9 MJ/day (220 kcal/day) for US adults comparing 2005 with 1978. For an adult above BMI 35, representing 14% of the US population, it is greater than 2 MJ/day (500 kcal/day).
So the small number describes how the weight arrived; the large ones describe what undoing it costs — and Hall states the second explicitly: ”the large change of average energy intake characterises the magnitude of the public health challenge.” A page using this record to argue that small changes suffice is using it against its own argument.