Cold Plunge and Appetite: What the Data Shows
Key insights
- In a 2025 randomised crossover trial, 15 healthy adults ate 2783 kilojoules at a buffet meal after 30 minutes of immersion in water at 16 degrees, against 1817 kilojoules after thermoneutral water and 1894 kilojoules after resting in air. That is roughly 230 extra kilocalories from a single plunge 1.
- The same trial found no difference at all in subjective appetite ratings between conditions. People did not report feeling hungrier; they simply ate more, which is why self-monitoring is a poor safeguard here 1.
- The effect is not new. Men who cycled for 45 minutes in water at 20 degrees consumed 877 kilocalories afterwards, against 608 kilocalories after the same session in water at 33 degrees, a 44 per cent increase 2.
- There is a plausible hormonal signal behind it. Overweight adults who walked for 45 minutes at 8 degrees showed a greater rise in acylated ghrelin, the appetite-stimulating form, and ate more afterwards than when they walked at 20 degrees 4.
- The practical consequence is narrow but real: a cold plunge is a poor tool for creating an energy deficit, because the compensatory intake it triggers is larger than the energy the exposure itself costs. It remains a reasonable tool for recovery, mood and thermal adaptation.
Cold plunging is frequently sold on its metabolic effects. Shivering burns calories, brown adipose tissue activates, and the implication is left hanging that a habit of cold exposure will, over time, shift body composition. The energy expenditure side of that claim is defensible. The problem is that expenditure is only half of an equation, and the other half has been measured surprisingly rarely.
When researchers have measured it, the answer has been consistent for two decades: cold water makes people eat more afterwards. Not dramatically more, and not because they consciously feel hungrier, but reliably enough that the extra intake tends to exceed whatever the exposure cost. A trial published in 2025 is the cleanest test of this yet, because it used passive immersion rather than exercise, which removes the confounding effect of a workout on appetite.
What follows is the mechanism, what each of the relevant trials actually found, and how to structure a plunge routine if body composition is one of your goals.
The mechanism: afterdrop, not hunger
Getting out of cold water does not end the cooling. Blood that has been sitting in chilled peripheral tissue returns to the core as vasoconstriction relaxes, so deep body temperature continues to fall for a period after the exposure ends. This is the afterdrop, and in the 2025 trial it persisted for 15 minutes following immersion at 16 degrees 1. The body is, in effect, still defending its temperature well after you have towelled off.
Defending core temperature costs energy, and the systems that regulate energy balance appear to register that cost. The authors of the 2025 trial proposed the afterdrop as the driver of the compensatory intake they observed, while noting that this has not yet been tested directly 1. What makes the hypothesis attractive is that it explains the most peculiar feature of the data: the eating response and the feeling of hunger came apart entirely.
What the 2025 passive immersion trial found
Fifteen healthy, physically active adults, ten men and five women, completed three randomised trials: 30 minutes immersed in water at 16 degrees, 30 minutes in thermoneutral water at 35 degrees, and 30 minutes resting in ambient air at 26 degrees. Energy expenditure, ad libitum energy intake at a subsequent meal and subjective appetite were all measured 1.
Intake after the cold trial was 2783 kilojoules, against 1817 kilojoules after thermoneutral water and 1894 kilojoules after air. The gap of roughly 950 kilojoules, or about 230 kilocalories, is larger than the additional energy a half-hour immersion of that intensity plausibly expends. And the appetite questionnaires showed nothing: no difference in reported hunger, fullness or desire to eat between the three conditions 1.
That dissociation is the finding worth carrying away. A response you cannot feel is a response you cannot manage by paying attention to how you feel.
The older exercise trials point the same way
The first clear demonstration came in 2005. Eleven men cycled for 45 minutes at 60 per cent of VO2 max on a submerged ergometer in water at 20 degrees and, on a separate occasion, at 33 degrees, with a resting control. Post-exercise intake was 877 kilocalories after the cold trial and 608 kilocalories after the neutral one, 44 per cent higher after cold and 41 per cent higher than rest 2.
A 2011 trial complicates the picture usefully. Ten trained men ran for 40 minutes and then spent 20 minutes in water at 15 degrees, water at 33 degrees, or resting out of the water. Both immersion conditions produced greater intake than the control, at 4893 and 5167 kilojoules against 4089 kilojoules, and cold water was not distinguishable from neutral water 3. Immersion itself, and the hydrostatic and postural conditions that come with it, may account for part of the effect independent of temperature.
Cold air produces a smaller version of the same response. Sixteen overweight adults who walked for 45 minutes at 8 degrees ate 1299 kilocalories at a buffet 45 minutes later, against 1172 kilocalories after walking at 20 degrees, and the rise in acylated ghrelin during exercise was significantly greater in the cold 4. That is the closest thing available to a hormonal fingerprint for the effect.
Realistic expectations
These are small, short-term laboratory studies. Between them they cover fewer than 60 participants, mostly men, mostly young and physically active, and every one measured intake at a single meal within an hour or two of the exposure. Nobody has yet followed a group of habitual plungers for months to see whether the compensation persists, shrinks with adaptation, or is offset later in the day. The honest summary is that the acute effect is well replicated and the chronic effect is unknown.
What the evidence does not support is the inverse claim, sometimes made in the other direction, that cold exposure suppresses appetite. It does not, at least not in water. It also does not mean cold plunging causes weight gain; it means the modest expenditure it produces is unlikely to survive contact with an unmanaged meal afterwards. We covered the expenditure side of that ledger separately in does cold plunging burn calories.
Practical guidance
Decide the post-plunge meal before you get in. The compensation showed up in ad libitum buffet settings, where participants chose freely. A meal that is planned and portioned in advance removes the mechanism by which the extra energy arrives. If you plunge in a fasted state, this matters more, not less.
Rewarm deliberately, and give the afterdrop the 15 to 20 minutes it needs. Dry off, put on warm clothing, move gently, and have a warm drink. If the afterdrop hypothesis is right, shortening the period during which the body is still defending its temperature is the most direct lever available. It is also simply better practice after cold water for other reasons.
Do not read your own hunger as a signal. The 2025 trial is unambiguous on this point: appetite ratings were identical across conditions while intake differed by more than 50 per cent 1. Judge the routine by what you actually eat over a week, not by how hungry you feel walking away from the tub.
And choose the plunge for the reasons the evidence supports. Recovery from strenuous training, mood and alertness, thermal tolerance and the discipline of a daily practice are all better-supported reasons to own a cold plunge than an energy deficit. Buying one as a weight-loss device is buying against the data.
The Contrast Market Perspective
Every trial described here specifies its water temperature to the degree, because a degree is the dose. A plunge that drifts from 10 to 14 degrees across a week is not delivering the exposure you think you are taking, and neither the recovery literature nor the appetite literature tells you much about what you are actually getting. That is the whole case for a properly specified chiller, accurate sensing and reliable insulation: not luxury, but the ability to know what you did. If you want help matching a unit to the protocol you intend to run, Schedule a consultation and we will work through it with you.
References
Footnotes
- Grigg, M. J., Thake, C. D., Allgrove, J. E., & Broom, D. R. (2025). Effects of cold-water immersion on energy expenditure, ad-libitum energy intake and appetite in healthy adults. Physiology & Behavior. [PubMed] ↩︎
- White, L. J., Dressendorfer, R. H., Holland, E., McCoy, S. C., & Ferguson, M. A. (2005). Increased caloric intake soon after exercise in cold water. International Journal of Sport Nutrition and Exercise Metabolism. [PubMed] ↩︎
- Halse, R. E., Wallman, K. E., & Guelfi, K. J. (2011). Postexercise water immersion increases short-term food intake in trained men. Medicine & Science in Sports & Exercise. [PubMed] ↩︎
- Crabtree, D. R., & Blannin, A. K. (2015). Effects of exercise in the cold on ghrelin, PYY, and food intake in overweight adults. Medicine & Science in Sports & Exercise. [PubMed] ↩︎