Pete Wright:
Welcome to Build for Health, a show that redefines strength because muscle isn’t just for looks. I’m Pete Wright, and I’m here with Coach Srdjan Injac. And today we’re talking about metabolism. Why do I need to think about metabolism in the gym, Srdjan? What’s the big deal?
Srdjan Injac:
Oh, it’s very important. People usually complain about their metabolism. They come to me and they’re like, I’m a little older, my metabolism is slow, and this and that, and they blame the age and all this stuff. So yeah, I hear a lot of complaints from people about their metabolism.
Pete Wright:
Well, to me it seems like it’s a mystery switch. It’s a switch that I feel like sometimes is flipped on and I can move mountains. I can eat mountains.
Srdjan Injac:
Yes.
Pete Wright:
And sometimes it’s just not. And I go into caloric restriction and weight does not come off. Doesn’t matter what I do. So I feel like there are things I don’t understand about what it’s doing and what I’m doing. If you ask me, is there anything I could do to impact my own metabolism? I would say no, hire a wizard.
Srdjan Injac:
There’s a lot of stuff that’s impacting your metabolism. Metabolism is highly adaptable. It depends on your lifestyle. There’s so many things that can affect your metabolism. People just don’t really know about all those things, and it’s an easy fix. It’s not that complicated to fix, but there are things that people are doing without realizing those are the things that are affecting their metabolism and the reason why they’re not burning as many calories and losing weight.
Pete Wright:
Okay, so walk me through it. What goes into metabolism? What do I need to know?
Srdjan Injac:
So first, to know what metabolism is — it’s the sum of all the chemical processes your body uses to keep you functioning, keep you alive. It’s everything from breathing, pumping blood, to repairing tissues, digesting food, building muscle, producing energy. So when most people talk about metabolism, they’re usually referring to how many calories the body burns every day, known as total daily energy expenditure.
Now this is made up of four major components. The largest, the biggest component is your basal metabolic rate, the BMR. Most people know about that. It’s the energy your body uses at rest to support those essential functions like your heart, brain, liver, kidneys. The second component is TEF, thermic effect of food. People don’t know this one. It’s the energy required to digest and process nutrients, to digest all the food that you’re eating.
Pete Wright:
Okay, so far you’ve just taught us two things, and I’ve already learned that what I thought I knew was completely wrong. I thought that basal metabolic rate was the food thing, and I didn’t know the food thing existed. So basal metabolic rate and thermic effect of food. There’s one and two. What is number three?
Srdjan Injac:
Number three is the activity, the exercises. That includes your workouts that you do at the gym, you have a workout plan and stuff like that.
Pete Wright:
Yeah.
Srdjan Injac:
And the fourth is the one that we kind of touched on the last time we talked about it in the show. It’s NEAT, the non-exercise activity thermogenesis. Those are all the movements that you do outside the gym, besides your workout — walking, standing —
Pete Wright:
This is your ten thousand steps.
Srdjan Injac:
Yes, your daily chores and stuff like that. A lot of people, there’s a big misconception. People say, I have a broken metabolism, not knowing that metabolism is very adaptable. It changes based on your body size, muscle mass, age, hormones, diet, sleep, stress, how much you move, all that stuff.
Pete Wright:
Well, it sounds like I say my metabolism is broken, but if I spend ten hours a day sitting at a desk, that may be a hint, Sherlock, about why my metabolism is broken — because of the NEAT.
Srdjan Injac:
Yes. So we’ll dive into all those four major components and try to keep it short and simple but also give more information so people will understand a little bit more. We’ll start with the BMR, the first one. It’s the number of calories your body burns just to keep you alive. So even if you stay in bed all day and you don’t move, your body will still need energy to power your heart, lungs, brain, hormone production, immune system, stuff like that.
For most people, that BMR accounts for about sixty to seventy-five percent of total daily calorie expenditure, making it the largest part of your metabolism. The biggest factors that influence BMR are your body size and lean muscle mass. So larger individuals and people with more muscle generally burn more calories at rest because muscle tissue requires more energy to maintain than fat tissue.
Pete Wright:
Okay.
Srdjan Injac:
Age, genetics, hormone levels, and long-term dieting can also affect the BMR, but not nearly as dramatically as many people think. Your organs are working twenty-four-seven. That’s where most of your energy is being used.
Pete Wright:
And there’s not a lot you can do to say, oh, kidneys, work harder.
Srdjan Injac:
Yeah, that’s why we always say it’s not just important what you do in that one hour of your workout. It’s what you do during those other twenty-three hours when you’re not at the gym. Those are the important parts. But the workouts are also important because they’re building the muscle mass. So it’s all connected. Now we have the second one, the food, the thermic effect of food.
Pete Wright:
Thermic effect of food, yeah.
Srdjan Injac:
That’s the energy your body uses to digest, absorb, and process the nutrients that you eat. Your body has to expend energy to break down the food and turn it into usable fuel and building blocks. Protein has the highest thermic effect. It means your body burns more calories digesting it compared to fats and carbs.
Pete Wright:
Okay, so I eat a good steak.
Srdjan Injac:
So here are some of the numbers. Protein is twenty to thirty percent of calories consumed. It’s used for digesting.
Pete Wright:
So for every — it uses thirty percent of the calorie to digest that calorie.
Srdjan Injac:
Yes. Those calories that you consume with the protein, about twenty percent of those goes into digestion.
Pete Wright:
Okay, got it.
Srdjan Injac:
Now carbs are anywhere from five to ten percent, and fats are like three percent.
Pete Wright:
So that’s why they stack up.
Srdjan Injac:
This is the reason why those high-protein diets can be beneficial for fat loss and muscle retention. That’s why I always say high protein, high protein. People that are losing weight, they’re like, well, I watch the calories. I’m like, eat the protein. High protein. It will help. So your body actually burns calories digesting that food, and the protein is the most metabolically expensive nutrient to process. So eat the protein. I can’t stress enough how important it is. Keep that in mind.
Now the third — it’s exercise activity thermogenesis.
Pete Wright:
Exercise activity thermogenesis. EAT. Which is ironically not involving food.
Srdjan Injac:
Yeah, EAT. Not involving food at all. So those include all the structured exercise — weight training, cardio, any sports, classes that you take, or workouts that you put together. It improves cardiovascular fitness, it builds muscle, strengthens the bones, and supports mental health as well.
But many people are surprised when they learn that exercise often makes up just a small portion of that daily calorie burn that they expect. Depending on training volume, it may account for around five to fifteen percent of total energy expenditure.
Pete Wright:
That’s pretty small.
Srdjan Injac:
It’s pretty small. People get really surprised by that.
Pete Wright:
Wow.
Srdjan Injac:
It doesn’t mean the exercise is not important. That’s why the resistance training helps you build and preserve the muscle, which increases that resting metabolic rate that we talked about. And cardio also improves heart health, endurance. Exercise also helps regulate appetite, insulin sensitivity. So it is important. Just because it doesn’t burn all those calories does not mean it —
Pete Wright:
It’s part of the system that does burn those calories.
Srdjan Injac:
Exactly. It will build the system that does. So it’s very important for the health and the body composition.
So the fourth one is NEAT, the non-exercise activity thermogenesis. Those are the movements outside the gym — walking, standing, cleaning, taking the stairs, getting the groceries, things like that. This is often the most underestimated component of metabolism. That’s why we say make sure you get your steps in. Ten thousand steps. They don’t see why it’s so important. They’re like, I’ll just go to the gym and work out and I’ll get there. It’s like, no, you gotta pay attention to those twenty-three hours.
Pete Wright:
What’s the thinking behind that? Set that up for me, because I’m thinking, okay, if I go to the gym and I work out really hard — I’m just saying that because I’m — I don’t just think this way, not me personally, as you know. I wouldn’t want to out myself as someone who thinks this way. But if I go to the gym and I work out really hard, doesn’t that make up for the ten hours that I sat in my chair all day?
Srdjan Injac:
My God, no. During that workout, you’re breaking down the muscle, you’re building the muscle, all that stuff. It doesn’t burn as many calories as you would burn if you just get up and walk and stuff like that. So someone who’s on their feet all day and walking can burn substantially more energy than someone who sits most of the day or just goes for one hour at the gym. Your body cares more about what you do in those twenty-three hours than just that one hour.
Pete Wright:
Okay, that’s the thing I have to — I want to make sure we wrap our heads around — there’s a compounding interest that goes into burning calories. And if you keep your body up at a certain level of constant activity, even just a little bit, that’s going to have a greater effect than the massive roller coaster of being very active to being completely sedentary to being very active to completely sedentary. That’s a fair way to look at it?
Srdjan Injac:
That’s a fair way to look at it. Exactly. All these components, they have different benefits. They do different things. But they’re all connected. So those are the most important components people should be aware of.
Now we can talk about sleep, stress, and hormones. They all also play a massive role in metabolism, recovery, body composition, just overall health. You can train hard and eat clean, but if your sleep and stress are poor, your body becomes less efficient metabolically.
Sleep is when the body repairs the muscle tissue you break down at the gym. It regulates hormones, restores the nervous system, and improves recovery. So when people are constantly under-slept — which I’m guilty of sometimes, I’ll admit I need to get more sleep, and I try to —
Pete Wright:
Yeah.
Srdjan Injac:
The body starts to shift hormonally in ways that increase hunger and cravings, while decreasing energy and performance. Hunger hormones like ghrelin tend to rise, and satiety hormones like leptin can decrease. Those are what we call hunger hormones.
Also, insulin sensitivity will worsen. People will naturally crave higher-calorie foods, sugary food, because the brain is searching for quick energy. So people are more likely to grab sweets and carbs, something with sugar, to get that quick energy.
Pete Wright:
It does work. It’s just fine for quick energy, but at what cost?
Srdjan Injac:
Yeah, exactly. So make sure you get your sleep. It will affect everything. People don’t realize they need those seven to eight hours of sleep. Probably the best way — try not to go under seven. Make sure the body can do its own thing once it’s asleep. That’s when it’s in repair mode. You’re not moving. So it’s important.
Now, stress. Stress affects the metabolism in a very similar way. A lot of people hear the word cortisol and immediately think it’s bad, but cortisol is actually a necessary survival hormone. It helps regulate energy, blood sugar, alertness, and the body’s stress response. The problem is chronic stress — where your body stays under constant pressure for weeks or months without any sleep, recovery, or downtime.
Pete Wright:
Can we sidebar on this?
Srdjan Injac:
Okay.
Pete Wright:
I’m curious — at the gym, what does it look like when somebody who’s experiencing chronic stress comes in? Can you think about that? Because in my experience, there are people who live in a state of high cortisol all the time, chronic stress, and don’t really know it, because they’ve adjusted to it. That’s just normal.
Srdjan Injac:
That’s where the workout helps. It really does help them with that. After the workout, they actually say, oh, I feel much better. I’m so glad I came in. I can actually think clearly. I feel better. It helps with that chronic stress.
But a lot of people go through that, and chronic stress increases emotional eating, cravings, fatigue, and recovery issues.
Pete Wright:
It totally makes you check your own assumptions about what it means for you to be healthy. Those assumptions may end up being false. You’re making assumptions about why your weight is doing what it’s doing, or your cardiovascular system is doing what it’s doing. And if you’re not in touch with the fact that you’re in chronic stress —
Srdjan Injac:
It affects everything. Psychologically, the body often doesn’t distinguish much between emotional stress, financial stress, lack of sleep, relationship problems, overthinking, or excessive dieting. It just signals stress. And over time, it can leave people feeling mentally drained, just exhausted, and stuck in that cycle where they’re trying harder but nothing’s happening. They’re just recovering worse. So it’s the chronic stress that’s bad.
Now hormones. Hormones themselves are deeply connected to metabolism and fitness. Hormones help regulate appetite, energy use, muscle growth, fat storage, recovery, mood, and even motivation. Insulin helps control blood sugar and nutrient storage. Thyroid hormones strongly influence metabolic rate and energy production. Testosterone supports muscle mass and recovery. And hunger hormones like leptin and ghrelin help regulate hunger and fullness.
What’s important for people to understand is that hormones are highly influenced by lifestyle habits. So consistent resistance training, adequate protein intake, quality sleep, stress management, and maintaining muscle mass all help support healthier hormonal function.
Pete Wright:
When you tell me that leptin and ghrelin influence fullness and hunger, it just makes me say, how do I naturally stimulate the one that makes me not want to eat so much?
Srdjan Injac:
If you don’t get enough sleep, those are the ones that get worse. The one for fullness gets declined, and you feel like you’re never full.
Pete Wright:
Okay. Those are the craving hormones.
Srdjan Injac:
Yes, those are the craving hormones. When you’re not getting enough sleep, you crave all this sugary stuff, and that gives you that boost of energy that you want. So if you can get everything under control, it will help that hormonal function. That’s why all that extreme dieting, chronic stress, lack of sleep, and poor recovery can push the body in the opposite direction.
So real metabolic health is not just about burning calories. It’s about creating an internal environment where the body can function, recover, and regulate itself properly.
Pete Wright:
Let’s talk specifically — you’ve already mentioned the value of resistance training. Can we talk specifically about how each of the major exercise functions hits our metabolism?
Srdjan Injac:
Yeah, so usually people are like, is it better to do resistance training or cardio? Which one would be better? Both cardio and resistance training are valuable, but they affect the body differently.
Cardio is extremely effective for increasing calorie expenditure during the actual workout. Running, cycling, stair climbing, rowing, similar activities — they burn a significant amount of calories relatively quickly, which is why many people kind of do that, people who are trying to lose fat. Cardio improves cardiovascular health, endurance, heart function, all this stuff.
The problem is many people rely only on cardio for weight loss, while forgetting and neglecting muscle mass and strength training, which can create problems in the long term if you don’t work on those.
Resistance training impacts metabolism differently because its biggest benefits are more long-term and structural. It helps build and preserve muscle tissue. And muscle is metabolically active tissue that requires energy to maintain. More importantly, maintaining muscle during fat loss helps prevent that metabolic slowdown that often happens with aggressive dieting or excessive cardio.
When people lose weight too quickly without resistance training or eating enough protein, they often lose muscle with fat. That muscle loss reduces strength, lowers recovery capacity, worsens body composition, and contributes to a lower metabolic rate over time. The metabolism just slows down.
Pete Wright:
Okay, so I’m starting to put together a picture. But for people like me who are saying, hey, I feel like my metabolism may need to be somehow kick-started, like I’ve reached a point of stasis — it sounds like my focus should be first on sleep, making sure that I’m getting the right sleep and enough of it.
Srdjan Injac:
Yes. Look at the stuff you can — everyone focuses on the workout itself. Focus on the things first that you can fix. Workouts, getting in the gym, working out — finding a trainer can help you with that. That’s easy. Just try to focus on sleep. Try to focus on managing your stress. That will help a lot. Focus on all these little things, like getting your ten thousand steps and moving more, not sitting at your desk for hours and hours. That can have an effect. Just your workouts going in is not going to solve the problem.
So try to focus on those things and try to take control over those things that you can change. You don’t need anybody for that. You can change those. Once you start taking control over that, you’re going to actually start feeling it right away and seeing the results without even actually going to the gym right away. Your mood’s gonna be different, the energy level, everything. You’re gonna start feeling the results right away. And then the gym is just gonna add on top of that and make it that much better.
Focus on the small things. Take small steps. Make small goals. Goals that are realistic.
Pete Wright:
Okay, I got it. I mean, I know I’m supposed to come in right now, but I feel like I need a nap. I’m gonna start with a nap and then a steak. It’s gonna be great.
Srdjan Injac:
When it comes to working out, the best approach for people is not just choosing cardio or resistance training — it’s a combination of both, strategically. Cardio supports heart health, endurance, calorie expenditure, all that stuff, and resistance training —
Pete Wright:
Yeah. I’m really glad we’re doing this topic, because we had a listener question, and I think it relates.
Srdjan Injac:
Mm-hmm.
Pete Wright:
The question came in anonymously. It says, how do you program around a job that is physically demanding? Does manual labor count as training? It sounds like, from this conversation, that labor, like regular activity, is a part of overall metabolic processing, and that’s awesome. But also, if you can find a way into the gym, that’d be good too. What’s your stance?
Srdjan Injac:
Yes, definitely. It doesn’t replace the whole workout. It’s included in those twenty-three hours, what you do when you’re not working out. Workouts are more intentional — you’re breaking the muscle down and all that stuff.
It depends what kind of labor, what kind of job. I’m sure they’re moving a lot, picking up stuff. It’s all more muscle endurance and stuff like that, which is great. It’s going to help. But he’s probably burning a lot more calories and he’s more hungry, and if he can just focus on his protein intake — he should try to find the time to actually do the resistance training, do some cardio, and that’s gonna make his job even easier.
Pete Wright:
Mm-hmm.
Srdjan Injac:
It’s just gonna help.
Pete Wright:
Okay. Just gonna help. That’s the deal. All right. Super useful. Take a look at those show notes — I’ll put as much detail in there as I can discern here, so you have a checklist of some things to look into and how to make some change in your own life and your own body.
Don’t forget, check out elev8fitnesspdx.com to learn more about the gym, to learn more about Srdjan and the trainers who work there. Awesome, awesome, awesome place.
We are so glad you joined us for the show today. If you’ve got questions about training, recovery, or how to make strength work in your life, we want to hear them. Head to the show notes again — there’s a link that says “submit a question to the coach,” and we’ll answer it in an upcoming episode.
Don’t forget to subscribe and share the show. This is how we grow stronger together. Thanks for listening to Build for Health. We’ll see you in the gym next week.
