By Eric Trexler, PhD
Note: the figures in this article come from the MASS Research Review
If you’re trying to lose fat, it’s all about creating a calorie deficit. Conceptually, that’s pretty simple: move more and/or eat less. But in practice, things get a bit more difficult. When we say “move more,” are we talking about doing more resistance training, more cardio, or just more general movement throughout daily activities? What are the ramifications of altering each type of activity, and how much does each change actually “move the needle” in terms of total energy expenditure? And where does dieting come into play – should we be leaning more on moving more, eating less, or a specific combination of both? There are a lot of decisions to make (and a lot of tradeoffs for each), but fortunately we have plenty of research to guide our way.
Components of Total Daily Energy Expenditure
Any discussion about creating an energy deficit requires a quick primer on energy expenditure. Total daily energy expenditure (TDEE) is exactly what it sounds like: the overall number of calories we burn over the course of a day. This is divided into sub-components including basal metabolic rate (BMR), thermic effect of feeding (TEF), exercise activity thermogenesis (EAT), and non-exercise activity thermogenesis (NEAT). BMR is often referred to as resting energy expenditure (REE), whereas the other components (TEF, EAT, and NEAT) are collectively considered non-resting energy expenditure (NREE). The components of energy expenditure are summarized in Figure 1.
Your BMR describes the amount of energy it takes to simply allow you to exist; that is, if you laid around in bed all day and did virtually nothing. Turns out, there’s a lot of stuff going on in your body, even when you’re pushing the upper boundaries of laziness. So, BMR typically makes up about 60-70% of daily energy expenditure. Resting metabolic rate (RMR) is quite similar to BMR, and the terms are often used interchangeably despite a very subtle distinction. Measuring BMR generally requires that the individual fasts for 8-12 hours and actually stays in the lab overnight so they can be measured directly upon waking. In contrast, RMR measurement allows for looser pre-testing standards and does not require an overnight lab visit, so it tends to be a tiny bit higher than BMR.
If you wanted to be slightly more “active” and work a couple of meals into your bedridden day, the thermic effect of feeding would describe the amount of calories used to ingest, absorb, metabolize, and store nutrients from food. If you’re eating at a maintenance level of caloric intake, this would take up another 10% or so of daily energy expenditure, but can fluctuate if you’re eating more or less than maintenance. Depending on how much you exercise, exercise activity thermogenesis could take up a huge (or negligible) proportion of your daily energy expenditure, so assigning a percentage can be tough. It’s common to attribute about 5-10% of daily energy expenditure to exercise, but this is highly variable. That leaves us with NEAT, which describes “everything else” that burns energy. Fidgeting in your chair, vacuuming your living room, and just about any non-exercise movement gets lumped in, and it’s generally estimated to contribute roughly 15% of daily energy expenditure.
Now that we know which energy expenditure “levers” exist, let’s figure out which one(s) to pull when we want to create an energy deficit.
Burning More Calories While Lifting
Lifting weights involves muscular activity, which means we’re going to burn calories in the process. But exactly how many calories are we talking?
In 2021, João and colleagues measured energy expenditure during three different full-body resistance training protocols with varying set and repetition schemes. In all three workouts, participants did the same 8 exercises (chest press, pec deck, squat, lat pull-down, biceps curl, triceps extension, hamstrings curl, and crunch machine) in order. The low-intensity protocol consisted of 2 sets of 15 repetitions of each exercise at 60% of 1RM, the moderate-intensity protocol involved 3 sets of 10 reps at 75% of 1RM, and the high-intensity protocol required 6 sets of 5 repetitions at 90% of 1RM. All three protocols included two-minute rest periods between sets and exercises, so the high-intensity protocol took much longer to complete than the low-intensity protocol (116 minutes versus 44 minutes).
While the high-intensity protocol led to greater absolute energy expenditure (total kilocalories burned during the full protocol), all three protocols induced pretty similar rates of energy expenditure (kilocalories burned per minute). Rate of energy expenditure was slightly lower when progressing from low-intensity to moderate-intensity to high-intensity, but all fell within the 5.3-6.5 kcal/minute range, with 6 serving as a suitable average value. However, this value will likely vary (to some extent) based on a wide range of program characteristics, such as training split, exercise intensity, rest period duration, and the exact exercises selected, among others. These minor distinctions can lead to detectable differences in the long run. For example, a 2024 study compared the effects of full-body and split-body resistance training programs with equated set volume on fat loss and delayed-onset muscle soreness. After 8 weeks, the full-body program resulted in greater volume load, less soreness, and greater fat loss. However, the magnitude of fat loss was not substantial, with the full-body training group losing only 0.775kg of fat in total.
At the end of the day, the goal of your resistance training program should be to induce the intended training adaptations. This involves applying an appropriate combination of frequency, volume, and intensity, while closely monitoring one’s recovery capacity and progress over time. In other words, you should design your lifting program to optimize power, strength, or hypertrophy – whatever you’re training for. Lifting is not a “calorie-burning” tool, despite the fact that calories get burned along the way. If you get too wrapped up in changing your lifting program to increase energy expenditure, you may end up sacrificing your power, strength, or hypertrophy. That’s not an advisable tradeoff, so you’re better off adjusting something else when trying to create a calorie deficit. I would only consider adjusting a resistance training program to emphasize increased energy expenditure or fat loss if I had extreme time constraints that made it impossible to incorporate other opportunities for physical activity throughout the week. In all other cases, we have better levers to pull.
Doing More Cardio
When people in the general population decide it’s time to lose a few pounds, cardio is often the first lever they pull. When you go to the gym in the first week of January, you’ll see rows and rows of treadmills full of novice joggers (and good for them – always be sure to contribute to a welcoming gym environment). But is that really the right choice for them, or for a lifting enthusiast like yourself?
There’s no question that cardio burns calories. When muscles generate force, they engage a multi-step process called “excitation-contraction coupling” – this describes the process of deciding to move a muscle, sending that message down the nervous system, and generating force (and then relaxing) at the muscle fiber level. Unsurprisingly, chemical energy (in the form of ATP) is used at several key steps of this process. The result is that movement causes us to burn energy, and more movement causes us to burn more energy. A massive project called the “compendium of physical activities” quantified the energy cost of over a thousand common physical activities; Table 1 shows a small selection of the estimated energy cost of key activities for a hypothetical person (180 pounds, 170 cm tall, 25 years old) exercising for an hour.
It’s a beautiful story – work hard for an extra hour a day, burn an extra 500 kcal/day, and there’s your calorie deficit. Unfortunately, that story unravels when you consider a pesky concept called “exercise energy expenditure.”
Back in 2016, Herman Pontzer published the seminal paper on exercise energy compensation. His hypothesis was initially inspired by some unexpected observations he made while conducting research with hunter-gartherer populations around the world. While they were dramatically more active than sedentary Americans, their daily energy expenditures were quite similar (after adjusting for body size). This led him to develop the constrained total energy expenditure model, which posits the following: As physical activity energy expenditure is pushed higher and higher (via increased physical activity), compensatory reductions in other components of energy expenditure will increasingly serve to constrain total daily energy expenditure. This would effectively work as a regulatory mechanism that preserves body energy and opposes continuous weight loss in response to large volumes of physical activity. This directly conflicts with the “additive model,” which is our intuitive assumption that adding 500 kcal/day of extra cardio will increase your total daily energy expenditure by 500 kcal/day. In reality, research repeatedly shows that your energy expenditure will generally increase when you add cardio, but considerably less than we would mathematically predict – especially if you were already quite active before making the increase. These models are contrasted in Figure 2, which is based on Pontzer’s work.
So, what are the downsides of relying on extra cardio to create an energy deficit?
There are two major drawbacks. First, it’s inefficient. When you dedicate the time and effort to a cardio bout that “should” add 500 kcal/day to your deficit, adaptive reductions in energy expenditure will directly undermine your efforts, such that the deficit increases by considerably less than 500 kcal/day. In many cases, the deficit may only grow by 200-300 kcal/day – that’s a heavy tax when you consider the time and effort invested. Second, the only way to overcome this “tax” is to do even more cardio. If you’re trying to create a substantial deficit, this amount of extra cardio could absolutely start to hinder your recovery and training adaptations, in addition to consuming amounts of time and effort that become difficult to justify. There’s nothing wrong with including cardio when you’re trying to lose some fat – it can make a small contribution, and it’s a fantastic thing to do for your general health and wellness. But as an independent fat loss tool, we’ve got way better options.
Reducing Energy Intake
I won’t bury the lede or craft a long-winded explanation for this: reducing energy intake is, by far, the best strategy for introducing a calorie deficit. Most people eat more calories than they need – this is the single best explanation for rising obesity rates over the last several decades. People are often amazed by how dramatically they can reduce their energy intake before they really start to “feel it,” as long as they’re using evidence-based strategies to navigate hunger and cravings.
The best approach is to start simple. Begin by minimizing your tendency to add sugar, oil, or high-calorie sauces to the foods you currently eat. Next, minimize your consumption of high-calorie beverages containing a bunch of sugar or alcohol. After that, make some easy food swaps: replace your high-fat foods with low-fat foods and replace your extremely high-carb foods with lower-carb options. Along the way, be sure to include plenty of high-fiber and high-protein foods with textures that require more chewing and a slower rate of eating. Finally, settle into a diet with “adequately palatable” foods – fairly repetitive from day-to-day, tasty enough to be tolerable, but not so tasty that you’re constantly obsessing over the next meal or snack. In many cases, these simple tips can make a difference of 1,000 kcal/day or more. They require no time, minimal effort, and shouldn’t threaten your recovery, performance, or training adaptations to the same degree as a ton of added cardio.
Of course, there is one complication to consider: metabolic adaptation.
Metabolic adaptation describes a group of physiological adaptations to the combination of energy restriction and weight loss, which collectively serve to oppose further weight loss. One of the most notable consequences of the metabolic and hormonal adaptations to weight loss is that our body becomes a bit more frugal with its energy use, resulting in fewer calories burned in a given day. Several studies spanning multiple decades have documented a disproportionately large drop in energy expenditure in response to weight loss diets.
The most pronounced effects of metabolic adaptation affect the NEAT component of daily energy expenditure. Through changes in total activity and (possibly) the metabolic efficiency of activity, reductions in NEAT appear to accompany weight loss and energy restriction. A great example of this phenomenon comes from the Biosphere 2 experiment, which is essentially the plot of a Pauly Shore movie called “Bio-Dome.” Eight individuals were placed in a self-contained dome environment, and they intended to maintain their own food supply by cultivating crops within the enclosure. They were relatively unsuccessful, so the study accidentally became a weight loss study. After two years of energy restriction, the weight-reduced participants emerged from the environment and a marked reduction in their NEAT was observed.
Considerable energy restriction often leads people to reduce their energy expenditure throughout the day via conscious and subconscious adjustments. Consciously, you might start using the elevator instead of the stairs, driving to places you would normally walk, or walking down to check the mailbox a couple times a week instead of every single day. Subconsciously, your friends and family might notice that you do a lot more leaning and sitting rather than standing, fidget less, use less animated gestures while talking, or that you slouch more than you used to (a postural adjustment to conserve small amounts of energy). If you happen to track your steps, you’ll often find that your daily step count drops dramatically as this process takes hold, unless you’re very proactive about keeping it stable. Evidence suggests that the combination of reductions in NEAT and exercise activity thermogenesis explain up to 85-90% of metabolic adaptation.
So, just like we saw with exercise energy compensation, the human body tries to use some compensatory adjustments to oppose diet-induced weight loss. However, the existence of metabolic adaptation does not mean that weight loss becomes impossible. It just means you’ll need to go a little further with your dietary adjustments to create and maintain the desired caloric deficit.
Increasing Non-Exercise Activity Thermogenesis (NEAT)
Non-exercise activity thermogenesis is the component of energy expenditure that nobody thinks about, but that’s a mistake. By some estimates, variations in this unstructured activity can yield differences in total energy expenditure of up to 2,000 kcal/day. I know that sounds completely incompatible with my prior statement that hunter-gatherers and sedentary Americans often have similar energy expenditure levels after correcting for body size. As it turns out, there’s a huge factor to consider: energy intake.
Energy intake is relatively low by default in hunter-gatherer communities. In America, excess energy intake is the norm. Recent research has indicated that exercise energy compensation is most commonly observed when people have limited caloric availability relative to their expenditure – for example, hunter-gatherers with limited access to easy calories, elite endurance athletes who are struggling to “out-eat” their massive training volume, or people who are intentionally restricting their calorie intake.
In addition, I’ll note that exercise energy compensation is nonlinear in nature. If you look back at Figure 2, you’ll see that increasing from extremely sedentary to moderately active is associated with a pretty straightforward increase in energy expenditure. In contrast, the “return on investment” (in terms of increasing total energy expenditure) gets way smaller if you’re increasing from very active to extremely active. So, we shouldn’t overlook the impact of being a little more active all day long. Walking short distances instead of taking the bus, standing instead of sitting, taking the stairs instead of the elevator – all of these small decisions can add up.
But the most important aspect of NEAT goes well beyond its independent impact on total daily energy expenditure. The main advantage of keeping non-exercise physical activity high when trying to lose fat is that it directly addresses the only “complication” of reducing energy intake. As discussed above, our bodies have a natural tendency to reduce NEAT when we’re on a weight loss diet. So, being more active while dieting isn’t actually about trying to drive your energy expenditure up to 5,000 kcal/day. It’s all about trying to proactively offset the potential reductions in NEAT that can occur when you go on a low-calorie diet. In this regard, increasing NEAT is a very helpful strategy that serves to complement dietary restriction rather than a standalone method for creating an energy deficit. For an added pair of bonuses, being more active is also good for your health and is extremely unlikely to hinder your resistance training recovery and training adaptations.
In practice, maintaining an adequate level of NEAT can be pretty simple. The easiest method is to track your steps (using a smartphone or wearable device) and aim for a daily goal. Most people will select a step count target somewhere in the 10,000 to 15,000 steps/day range to keep NEAT on the higher side without going totally overboard. There’s nothing to stop you from aiming for 25,000 steps per day, but you’ll likely find that extremely high step count targets can induce a compulsion to be perpetually walking. This compulsion can negatively impact your quality of life, and the tradeoff generally isn’t worthwhile. So, pick a sensible target that works for you and be proactive about maintaining it throughout the dieting process.
The Verdict
Cardio is one of the single best things you can do for your general health and wellness. But when it comes to creating an energy deficit, research points to a very clear winning combination: keep your NEAT high and use dietary changes as the primary weight loss tool. For body composition purposes, lifting should absolutely be a major part of the picture. However, the vast majority of lifters should be manipulating their resistance training variables for the purpose of facilitating gains in strength, power, or hypertrophy – not to burn more calories.
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Eric Trexler, PhD
IG: @trexlerfitness
