Generate more body heat at rest?

when I lost a substantial amount of weight, I went from always being hot to always being chilled.

Even now, in the 60’s, I wear socks and a fleece robe over my clothes around the house. Anything under 60, i need gloves to go outdoors.

My personal experience has been, with low body fat, you simply don’t have the insulation you used to have, and chill much easier.

Many many people here report similar

My go to so far this year has been a heating pad, fleece robe and slippers, and hot tea or broth when I’m particularly chilled. 🤷🏻‍♀️

Worrying about TDEE and BMr would just be diving headfirst into the weeds for me, when low body fat is the (my) culprit.

I’m fine when I get up and around and move.

YMMV but that would stick out to me with your low body fat %.

There's a question in my mind about the direction of causation when I read your post: Yes, metabolic rate contributes to how hot or cold people feel, but also people who have a higher core body temperature are going to have a somewhat higher metabolic rate, y'know? Which is the cause and which is the effect?

BF% around 11% is fairly low even for a man. Are you committed to staying that lean? I think there's some role of subcutaneous fat in sustaining core body temperature, but my main reason for asking isn't that. One strategy for increasing BMR/RMR - with very limited scientific evidence - is reverse dieting. That is very slowly and gradually increasing calorie intake in small increments, with the hope that body weight will stay constant and BMR/RMR will up-regulate. If that works, it might raise core body temperature a little, improve energy level, blahblahblah . . . but the risk is that if it doesn't work, the calorie increase would cause very slow body fat gain. This is iffy territory, speculative - and I know it.

I do think weight loss can lead to people being colder, and don't believe that the sole mechanism is reduced body fat "insulation". (I say that because I lost a bunch of weight in my teens, then was constantly cold. After losing a larger amount of weight in my late 50s, down to a similar body weight, I wasn't cold. I'm not totally sure why.) But you don't mention weight loss.

How is your overall nutrition? That can affect core body temperature, theoretically. Protein, fats, and fiber are the factors usually mentioned. Adequate hydration may also matter. (Urine should be pale yellow, like straw color, not dark yellow.)

How much cardiovascular exercise do you get now? If it's limited, there are diverse reasons to work up to the generic mainstream recommendation of 150 minutes of moderate cardiovscular exercise per week, 75 minutes of intense exercise, or a proportional combination of both; ideally spread over at least 5 days.

When it comes to body temperature, improved circulatory system health may make blood vessels respond more productively to heat and cold in the environment. There's some evidence that regular cardiovascular exercise over a reasonably long time can increase metabolism (RMR/BMR), beyond the short-term potential effect of EPOC and simple increased body temperature during the workout.

I think there's only limited evidence to support anything dramatic with body temperature, but if you're not getting much cardiovascular exercise now, the other benefits (non-temperature) can be quite significant, especially long term.

Interestingly - to me, at least - there's some limited research evidence suggesting that Tibetan tummo practice can increase body temperature in the short run, and maybe tend to increase metabolism overall as well. However, that's a pretty arcane, advanced practice . . . I think more effort investment than most people would care to make just in order to feel warmer in routine life. 😆 It's pretty wild and crazy stuff.

TL;DR: The cardiovascular exercise increase might be worth a try, especially if you don't get much of it now, and are prepared to make it a consistent long-trem practice. At worst, you'll get to eat more and stay around 11% BF. At best, you'll get an array of health benefits, and maybe/possibly better body temperature regulation.

Ok this is very similar to pranayama in yoga. Most my instructors do some form of these as a warm up before going into flow.

We do it both to relax and focus prior to vinyasa, and to warm the body to prepare.

Sounds like a combo of ujjayi breath and fire breath. We also -very occasionally-do the alternate nostril breathing. Cant thing if what its called.

My personal experience: I'm not cold when I'm active and right after, but at rest I'm an absolute icicle. I've lost a lot of weight, but I'm not particularly lean or anything. I can only presume that it has something to do with the weight-loss itself and/or the drastic change in insulation/body fat.

My 'solution': extra layers whenever possible, trying to keep active throughout the day (moving around the house/office, not just exercise) and I've also found that my afternoon hot cacao/coffee drink helps a lot - not sure if it's just the heat of the drink or also the caffeine.

I’ve idly wondered if being cold all the time doesn’t contribute to higher metabolism.

It would seem to make sense that our bodies have to expend more energy to get to and remain warmer. Just like turning up the household thermostat uses more energy.

I have zero basis in fact for this, just a vague notion that I find it noticeably easier to stay close to maintenance and I strangely feel thinner when the chills set in.

Oh, the tricks our heads play on us.

I'm currently eating more frequently than before (stomach issues) and I sure wish a benefit of that would be feeling less cold, but alas! 🥶

Whilst I’m sure there are some changes you can make to increase temperature a tiny bit (fidgeting maybe?) you might just feel cold. One of my former colleagues also had Raynaud’s and she just ran cold. All the time. Whereas I run hot and always have. In the office I’d be in t shirt and thin linen trousers feeling grumpy and hot, and she would be in multiple layers and still cold.

I know the grass is never greener, but I’d love to be cold. I’m sure it’s unpleasant, it would just make a change from being hot and sweaty all the time!