How alcohol increases food consumption.
What the evidence says
- The effect sits above a threshold rather than rising across the range. Caton and colleagues gave 12 men 0, 1 unit (8 g ethanol) or 4 units (32 g) thirty minutes before an ad libitum lunch; intake was significantly higher after 4 units (5786±991 kJ) than after 1 (4928±1245 kJ), and the paper states the finding as holding ”above a certain threshold”[1]
- Alcohol taken before a meal increases what is then eaten — at four units in Caton’s test, and as a general tendency in Yeomans’ review[1],[2]
- Two routes are offered, and they come from different sources: appetite stimulation, with hunger rated higher after 4 units while fullness was unchanged, and, in Yeomans’ review, ”probably” reward: ”alcohol consumed before or with meals tends to increase food intake, probably through enhancing the short-term rewarding effects of food”[1],[2]
- One unit did not produce the effect. The moderate case is the condition the study tested and excluded — and Yeomans’ review reports that moderate consumption may protect against obesity, particularly in women[1],[2]
- The short-term and long-term evidence disagree, and the review says so plainly: laboratory data show over-consumption while ”epidemiological data suggests that moderate alcohol intake may protect against obesity, particularly in women”[2]
- Energy consumed as alcohol ”is additive to that from other dietary sources, leading to short-term passive over-consumption of energy”[2]
- In mice, ethanol activates hypothalamic Agrp neurons, which are ”normally activated by starvation”, and the authors find that it can ”paradoxically sustain brain starvation signals” and drive overeating despite caloric sufficiency[3]