Why does hot weather instantly kill the appetite?

by 12108 · July 18, 2013 at 07:27 PM

What is the biological/chemical pathway to appetite suppression in the case of hot weather? I can go through a rainy cool week with an increased appetite (separate from the idea of being trapped inside/bored), but as soon as temps break 75 degrees or so my appetite seems to plummet.

I could understand appetite regulation due to weather/seasons' change over the long term, but even an unexpectedly one-off hot day in a longer stretch of cool weather can instantly affect my appetite.

ETA per developments in the thread: One thing I consistently do crave in hot weather is juicy, often high-fructose fruits. (Watermelon, cantaloupe, honeydew, berries of all kinds, etc.)

However, since I'm trying to lose weight and animal proteins and fats constitute the bulk of my menu, I can say that hot weather definitely kills desire for fatty or animal protein heavy meals. Anybody else experience this? How do I stay full/blood sugar steady in hot weather when I don't crave my usual high fat moderate protein foods?

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10 Replies

20222 · April 25, 2011 at 02:22 PM

Part of metabolism is simply to keep body temperature up. As it gets warmer, not as much energy is required to maintain body temp. Less output, less need for input. Oh my gosh! Did I just spout calories out = calories in? Oops!! (well, it is true but doesn't explain fatness - for that we have Taubes).

942 · July 18, 2013 at 07:27 PM

Either way, right now it is 93F, humid. I hope no one I know is eating blubber. I got home yesterday after one hour biking in this weather and I ate all the fruits in the house (about 2 lbs). Then I opened a 15 lbs watermelon and I ate 5lbs. This is no time to eat like the Inuits. In January, I will eat spoonfuls of tallow again. Right now is like it was when I was living in Brazil. Watermelon in particular lowers the body temperature while providing a lot of K and vitamins A and C, the Chinese consume the most watermelon in the world (in summer of course) because they have a good understanding of the medicinal properties of foods.

0 · July 18, 2013 at 03:12 PM

Believe me when i say 75 is very hot to the point where we have melt down and i find it unbearable :(. In the UK we havent had a summer in three years, our transport, homes etc are not made for warm weather and i can say....i have had enough after three days and cant wait for cooler weather.

Regarding food, i tend to drink more in this heat and eat less. Its far to hot to think of food or to even be bothered to eat it as this weather just seems to overwhelm me. A bbq is out of the question not unless its in a shady area and someone else is cooking.

One mans meat is another mans poison and personally, hot weather is when you go abroad for two weeks, enjoy ones self and return to a more decent climate where one can work, rest and play without overheating and being able to do so on full speed without the heat slowing one down.

7741 · April 27, 2011 at 04:23 AM

Doesn't happen to me, but happens to a lot of people. I definitely want COLD food and drinks when it's hot and I'm sweaty, but I still have a big appetite!

2143 · April 26, 2011 at 08:45 PM

I worked for two summers on the coast of NC as a sea kayaking guide. It gets over 100F there and we're paddling in hot sun all day. Two other guides (who happen to be male) that I work with have very little appetite out there. They typically only eat one meal per day, dinner, around 6 or 7pm. We paddle 15+ miles a day and then hike through deep sand across islands, and they seem to not get hungry. This amazes me, I eat 3 times a day plus snacks and drink about a gallon of water a day out there. I will say there are certain foods I definitely don't want to eat in the heat but I do get hungry. On a side note, I just came back from the middle east, so I went from 100degree weather to 60 degree weather in two days. For some reason (and it could very well be boredom) I find myself wanting to eat more often since I've been back and can't seem to satiate my cravings. I've been craving junk food much more since I've been back as well.

21258 · April 25, 2011 at 04:05 PM

It's all about the thermic effect of food. When I break fasts with feasts (think Churrasco and 2-3lbs of meat in one meal), I'll sweat even when it's cold out. It's because my body temperature is elevated due to the digestive process.

I eat less in the summer, maybe because deep down in my psyche, I don't want to be sweathoggin' at work.

3196 · April 25, 2011 at 03:57 PM

Wait, what? 75 degrees is hot weather? And it suppresses the appetite? Which would explain why the southern US has the highest rates of obesity? And why do people in the tropics have no problem eating? And how do we explain the phenomena of people eating delicious bbq in Texas in the middle of summer time?

Having lived in Texas for a decade, spent a fair bit of time in the Caribbean, and a good two plus decades in Southern California, I can say with some certainty that 75 degrees is not hot weather, and that it is has no effect on appetite for most people. Oh yeah, I lived in Minnesota too. 75 isn't even that warm for them in the summer time (but they start eating ice cream some where around 45 degrees).

I'm not saying you don't experience this phenomena on a real, physiological level, but it is probably some sort of gene x environment interaction specific to some genotypes. I mean we wouldn't have Thai cuisine if it weren't for someone getting a hankering to make delicious coconut curry when it is 98 degrees with 98% humidity. It is also worth noting that India is ridiculously hot and humid and, at least for those who can afford to eat, they have an obesity problem too.

Seriously though, there's few things better than Texas barbecue in the summer outside in the sweltering heat. With a cold beer. Yeah, that isn't paleo, but whatever.

25189 · April 25, 2011 at 03:24 PM

Hot weather stimulate NPY and increase appetite in most mammals to eat plentiful carbs in long light days.....it also stimulates reproduction. So I think you got it backwards. But it could also be that this is a symptom of a hormonal problem.

482 · April 25, 2011 at 03:07 PM

I think that on some level people have a subconscious knowledge of how much food they have access to. During the colder months, you would theoretically have less access to meat and certainly fruits and vegetables, so your body goes into a mode where it's "stocking up" on food.

I notice a similar effect when I'm low on money vs when I have a lot of money. The more money I have...the less hunger triggers I have.

I think it's a matter of your brain responding to scarcity and abundance differently.

That's my theory.

384 · April 25, 2011 at 02:49 PM

Digestion needs a lot of water in the process and I believe that the body downregulates appetite to keep more water in the system on a hot day to keep you cool.

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