I don't think I eat less, I think I eat more fruit and salad, perhaps for the water content. . . ? I know I don't feel like a heavy roast dinner, or the like, in hot weather and this is probably because it heats our internal oven, as the Chinese would say.
You have to eat regardless of the weather. It doesn't make much difference to us, as our stomach needs to be filled. If the weather is around 41 or 42C the only thing that changes is that we can't be bothered cooking in the heat. Cooking heats us up as well as the house. My mother refused to cook in extreme heat, as the heat from the oven or the grill would make the house ( and herself) hotter. In those days anything over 35 was hot. 40 plus temperatures were unheard of back then, when I was growing up, so things have changed. On those days, we would have lots of salads and cold meat. It was always good if we had a cool change, so that we could get back to eating a hot dinner. If we get sick of salads nowadays, my husband will go out and get some fish and chips from the shop. That way, we still get a hot dinner, but someone else has done the cooking. Eating in the heat doesn't really affect us too much, because we have a good air conditioner that cools the whole house. It doesn't cool as well if it is very humid though, and those are the days we eat salads. We still have to eat despite the heat, we just don't eat hot food.
I have a small appetite at all times,but I do eat a lot of fruit through every season of the year. I am not a comfort eater at all,thank heavens!! I do always have lots of yummy foods in my pantry and fridge,but it is more so that I can offer them when visitors come over!! I do love to share! Last week,my wonderful neighbour who does so much for me was having visitors and rather than him traipse out to the local supermarket in the dreadful heat,I could give him a packet od delicious little Desobry chocolate biscuits ,as I had bought several packs when they were heavily reduced after Christmas,despite 6 months till their use-by date! I really enjoy being able to do little things like this. This week I have eaten even less than usual,and I do attribute it to the terribly hot weather!
I definitely eat less and drink more in the hotter weather. Sometimes we have a BBQ with salad as veggies just seem to cut it when its hot. Other times we can't be bothered so have take-aways instead. Occasionally I will use the slow cooker with everything thrown in so only have to cook rice or pasta to go with it. Every weekend we eat out at our local Chinese and its airconditioned so we eat as normal.