Always Feeling Cold on Ozempic or Zepbound? Here’s What’s Really Going On
- Jennifer Hardy
- May 24
- 6 min read
If you’ve started taking Ozempic, Wegovy, Zepbound, or Mounjaro and suddenly feel like you can’t warm up, welcome to the club. Feeling cold on GLP-1 medications isn’t just in your head, and it’s not a weird fluke.
There’s actual science behind it, from how your body burns energy to the impact of losing fat and muscle. Here's what’s going on, what the research says, and what you can do to stay warm without walking around with a coat in the dead of summer.
For all my ladies out there in the throes of menopause (or perimenopause/post menopause), you probably won't experience this sensation. At least, not as much. I'll also explain why in the article below.
Thermogenesis 101: How Your Body Makes Heat
Your body has a built-in heating system called thermogenesis. It’s what keeps you warm when it’s cold out or when you haven’t eaten much. Most of that heat comes from your metabolism, but one lesser-known MVP here is brown fat.
Brown fat isn’t the stuff you’re trying to lose—it actually burns energy to make heat. It’s full of mitochondria (the little engines inside your cells), and it kicks in when your body needs to warm up.
Here’s how your body creates heat:
Basal metabolism: Just staying alive takes energy. Your body burns calories 24/7 to keep your organs running. On smart scales, it will display as the Basic Metabolic Rate (BMR). ⏬
Food digestion: Yes, eating actually warms you up. It takes energy to digest food, especially protein.
Movement: Working out gets you hot because your muscles are firing.
Brown fat: This one’s the wild card. It activates when you’re cold and burns calories just to create heat—no workout required.
Hormones help drive thermogenesis, too. Glucagon and GLP-1 (the hormones targeted by medications like semaglutide and tirzepatide) both influence energy use.
You're eating less, likely losing both fat and some muscle, and that means less raw material for heat production. Your metabolism may slow down a bit, and if your brown fat isn’t as active, that cold feeling creeps in. Add in less food = less fuel to burn = lower body heat. It’s a perfect storm for shivering, even when it’s not that cold out.
Wait! What's Brown Fat vs White Fat?
Not all fat is the same. Understanding the difference helps explain why you might be freezing on GLP-1 meds.
White fat is the storage fat most of us are trying to lose. It hangs out under the skin (that’s subcutaneous fat) and deep around your organs (called visceral fat, and yes, it’s the more dangerous kind). Its job? Store energy for later. It doesn’t do much to keep you warm.
Brown fat, on the other hand, is metabolically active. It burns calories to generate heat. It’s primarily found in small pockets around your neck, shoulders, spine, and upper back—basically your body’s built-in space heater.
Babies have a lot of it; adults, not so much. But when you’re cold or in a low-calorie state, brown fat can fire up to keep your core temp stable.
White fat (especially visceral fat) can slow down your metabolism over time. It releases inflammatory signals and hormones that can lead to insulin resistance, higher cortisol, and a sluggish metabolic rate. More visceral fat = more metabolic dysfunction.
Brown fat, though, does the opposite. It boosts metabolism by burning calories to produce heat (a process called non-shivering thermogenesis). It’s like your internal furnace. The more active your brown fat is, the more energy your body burns, even at rest.
Here’s the problem: when you're losing weight—especially fast—you’re usually shedding white fat and possibly some lean muscle. That means less insulation and less fuel for heat. If your brown fat isn’t doing enough to compensate, suddenly you're cold… all the time.
Understanding Basic Metabolic Rate
As noted earlier, your Basal Metabolic Rate (BMR) is the number of calories your body burns just to keep you alive. That means breathing, circulating blood, keeping your organs running, etc., without any movement at all. It’s basically your body's baseline energy burn, and it's a big piece of the metabolism puzzle.
Since starting GLP-1 medication, I’ve been tracking my BMR with a RENPHO Smart Scale. Honestly, I wasn’t expecting much. But the data surprised me.
Back in January, my BMR was sitting around 1527 kcal/day. That was Day 1 of my Zepbound journey.
Five months later, it's climbed to 1741 kcal/day. That’s a jump of over 200 calories my body now burns at rest. And yes, that's a good thing.
Now here’s the kicker: how warm or cold you feel is partly tied to your BMR. When your metabolism slows down, like when you're under-eating or losing muscle, you might feel colder.
On the flip side, if your BMR is going up, that usually means your body is using more energy, which can help maintain warmth.
So while some GLP-1 users feel cold all the time, tracking this trend has helped me understand what’s really happening beneath the surface.
Bottom line: a rising BMR is a sign my body’s still running strong, even with a reduced appetite. And it might explain why I’m not freezing as much as I used to, though perimenopause probably helps that (I'm 50).
Other Reasons GLP-1s Might Make You Feel Cold
Beyond brown fat and BMR changes, there are a few more subtle (and often overlooked) reasons why GLP-1 meds can leave you reaching for a hoodie in summer:
Muscle loss: Muscle mass helps generate heat. If you’re not prioritizing protein or strength training, your body might be burning fewer calories overall, even when at rest.
Dehydration: GLP-1s often blunt thirst cues. If you’re low on fluids and electrolytes, your circulation can dip a bit, especially to your hands and feet, making you feel colder.
Slower digestion: These meds slow down how fast your stomach empties, which means your body may stay in a low-energy, low-burn state longer throughout the day.
According to a 2019 review, GLP-1 and glucagon both play key roles in regulating thermogenesis and energy balance, suggesting that these hormones don’t just influence appetite, but also how much heat your body produces at rest.
What to Do If You’re Freezing on a GLP-1
If you’re constantly cold on GLP-1s, it doesn’t mean something’s wrong—it usually means your body is adjusting to a new metabolic baseline. Still, that doesn’t make it any less annoying.
One of the easiest ways to warm up is to eat more regularly, even if it's just small protein-rich snacks. Eating helps fuel thermogenesis, especially when you're getting enough protein.
Hydration also matters, but it’s not just about water. Your body needs electrolytes like sodium, potassium, and magnesium to keep circulation working efficiently (cold hands and feet are often the first sign something’s off there).
Movement helps too, even if it's just a brisk walk or some light stretching, can kick your body into a warmer, more active state.
If you’re tracking things like BMR or muscle mass on a smart scale, keep an eye on those trends—they can help explain shifts in how your body is generating (or not generating) heat.
And if the cold feels extreme or new, it’s worth checking in with your doctor. Thyroid issues, anemia, or nutrient deficiencies can also show up this way, and it never hurts to rule those out.
GLP-1 Cold vs. Perimenopause Heat
GLP-1 medications can make you feel colder due to fat loss, lower food intake, and metabolic slowdown. Meanwhile, perimenopause is famous for doing the opposite.
Here’s the thing: feeling cold and hot flashes come from entirely different systems in our aging bodies.
GLP-1 medications like Ozempic and Zepbound impact your metabolic system. That’s why your hands and feet might constantly feel cold, even when the thermostat says it’s 72 degrees.
Hot flashes, though? Those are a hormonal system issue, triggered by fluctuating estrogen levels messing with your hypothalamus; that's the part of your brain that regulates body temperature.
It’s not about actual body temperature changes; it’s about your brain misreading the signals and hitting the "overheat" button at random (usually at 2 a.m.).
Perimenopause may dampen the cold sensitivity some GLP-1 users feel, thanks to the competing effects of hormonal heat surges. However, you might experience both: cold all day from metabolic shifts, then sweating through your sheets thanks to perimenopause.
Getting Warmer While Being Safe
If you’re cold all the time on a GLP-1, it’s tempting to live under a blanket with a mug of hot coffee glued to your hand. And hey, sometimes that’s exactly what you need. But keep in mind: too much caffeine can actually make it worse by tightening blood vessels and slowing down circulation to your hands and feet.
As cozy as it sounds to stay still, movement is one of the best ways to warm yourself up. You don’t need to hit the gym. Just walking around the house, stretching, or standing up every hour can kick your metabolism into gear and help generate heat.
Your body’s adjusting in ways you can’t always see, but that doesn’t mean you’re powerless. Small shifts in food, hydration, and activity can go a long way in making you feel warm-blooded again—blanket optional.
