"Is cardio necessary for weight loss?" The answer to this question is not as simple as you think.
The true task of strength training during fat loss is to preserve muscle and metabolism; the saying "you only lose weight with cardio" is severely incomplete.
If you've ever searched for weight loss methods, you've almost certainly seen advice like: "Run for 30 minutes a day," "You only lose weight with cardio," or "Strength training doesn't burn fat." These statements have been circulating in fitness circles for a long time, but how accurate are they?
The answer is: partially correct, but severely incomplete.
In today's article, Coach Kai will start from the most fundamental principles to help you thoroughly understand the true relationship between cardio for weight loss, caloric deficit, TDEE, and fat loss through strength training. After reading it, you will find that the logic of weight loss is actually very clear—the real difficulty has never been the principle itself.
First, understand this: The essence of weight loss is a caloric deficit.
The only principle of weight loss is a caloric deficit. All diets that help you lose weight ultimately do so by creating a caloric deficit.
Before discussing cardio, a core concept must be established: the only principle of weight loss is a caloric deficit.
Whether you choose a low-carb diet, intermittent fasting, a Mediterranean diet, or any popular weight loss method, the reason they help you lose weight ultimately points to the same thing: creating a caloric deficit. Understanding this point makes all subsequent discussions meaningful.
What is TDEE? How many calories do you burn daily?
TDEE consists of BMR, EAT, NEAT, and TEF. The higher your muscle mass, the higher your basal metabolism, and the impact of daily NEAT activities should not be overlooked.
Since caloric deficit is key to weight loss, "calorie expenditure" becomes very important. The metric for how many calories a person burns daily is called TDEE (Total Daily Energy Expenditure).
TDEE consists of four components:
First: Basal Metabolic Rate (BMR)
This accounts for 60–70% of TDEE, making it the largest component. It refers to the minimum calories your body burns while completely at rest throughout the day to maintain vital functions—breathing, heartbeat, organ function, and cell synthesis. The heavier you are and the more muscle mass you have, the higher your BMR usually is.
This is why Coach Kai repeatedly emphasizes the importance of building muscle: the more muscle mass you have, the higher your basal metabolic rate, and the more calories you burn daily, even when doing nothing.
Second: Activity Level (EAT + NEAT)
This accounts for 15–30% of TDEE. Activity level is divided into two types:
- EAT (Exercise Activity Thermogenesis): Intentional exercise, such as going to the gym for strength training, running, swimming, or hiking.
- NEAT (Non-Exercise Activity Thermogenesis): All calorie-burning activities in daily life apart from intentional exercise—walking to commute, climbing stairs, doing housework, walking the dog, talking, getting up to pour water, these all count.
NEAT is often called the "secret weapon for weight loss." The time we spend on intentional exercise each day is at most one to two hours, but the remaining twenty-plus hours are spent on non-exercise activities. For someone without a regular exercise habit, NEAT can even account for a higher percentage of TDEE than intentional exercise.
What does this mean? If you genuinely don't have time to exercise today, instead of completely lying down, walk a few more steps, choose the stairs instead of the elevator, and get up and move around every now and then. These seemingly trivial actions, accumulated, can lead to much more significant calorie expenditure than you might imagine.
Third: Thermic Effect of Food (TEF)
This accounts for about 10% of TDEE. The body itself needs to expend energy during the process of digesting, absorbing, and storing food. Among nutrients, protein has the highest thermic effect of food, which is why increasing protein intake is recommended during fat loss—it not only helps maintain satiety but also allows you to burn a few more calories.
Fourth: Adaptive Thermogenesis
This accounts for a minimal percentage, with limited practical significance, and does not need to be specifically considered in daily fat loss planning.
Once you understand the components of TDEE, you'll realize that you can approach creating a caloric deficit from multiple angles, and cardio is just one of those options.
Cardio vs. Strength Training: Which burns more calories?
When considering immediate expenditure, cardio is more efficient than strength training; when post-exercise afterburn is included, the total expenditure of both is quite similar.
This is a question many people want to know. The answer is: if you only look at the calories burned during the exercise itself, cardio is indeed more efficient than strength training. For the same one hour of training, running typically burns more calories than strength training.
What about the "afterburn effect (EPOC)" of strength training? The afterburn effect refers to the extra calories the body burns after exercise to return to its original state. Strength training does have a higher afterburn effect than cardio, but for the average trainee, this extra expenditure is not that significant, and the effect comes and goes quickly, not lasting for several days.
If you calculate the calories burned during exercise plus the afterburn effect, the total calories burned by cardio and strength training are actually quite similar, with some studies even showing cardio having a slightly higher total expenditure. So, if your goal is simply to burn as many calories as possible in a short amount of time, cardio is indeed a more direct choice.
But here's the problem: does this mean you should do excessive cardio during fat loss?
What happens if you only do cardio during fat loss?
If you only do cardio and no strength training during fat loss, muscle loss will lower your basal metabolism, leading to easy weight regain even with slightly increased food intake later.
This is a very common misconception. In a caloric deficit state, your body may not only burn fat but also lose muscle. If there's no strength training during fat loss to signal the body that "these muscles are important, please keep them," muscle loss can be very rapid.
Muscle loss leads to a serious chain reaction:
- Decreased muscle mass → Decreased Basal Metabolic Rate (BMR)
- Decreased BMR → Fewer calories burned daily
- Fewer calories burned → The same diet starts to create a caloric surplus
- Result: It becomes easy to regain weight even with slightly increased food intake
This is why many people say: "I worked hard to lose weight before, but now it seems I gain it back easily even with a small amount of food." This is not a willpower issue; it's because your basal metabolic rate has significantly decreased due to muscle loss.
The true role of strength training during fat loss: goalkeeper, not fat-burning machine.
The core function of strength training during fat loss is to maintain muscle mass and preserve the basal metabolic rate, rather than direct fat burning.
It helps you preserve muscle mass and basal metabolic rate, allowing the entire fat loss process to be more sustainable and successful, rather than bouncing back faster after you've lost weight.
Coupled with adequate protein intake (generally recommended 1.6–2.2 grams per kilogram of body weight), strength training can help you retain as much hard-earned muscle as possible in a caloric deficit environment. This ensures that you lose true fat, not a mixture of fat and muscle.
A drop in the scale doesn't necessarily mean a better physique. True fat loss involves maintaining or even improving the muscle-to-fat ratio while losing weight. This is what Coach Kai refers to as "fat loss," not just "weight loss."
So, should you do cardio for weight loss?
Cardio is not a necessary condition for weight loss; consistently creating a caloric deficit is key, and methods can be flexibly chosen based on individual circumstances.
The answer is: not necessarily. Cardio is just one tool to help you create a caloric deficit.
There are many ways to create a caloric deficit—cardio, strength training, increasing NEAT, diet control—and none is "essential." What truly matters is whether you can ultimately create a sufficient and sustainable caloric deficit.
The methods themselves are flexible and can be adjusted based on your lifestyle, preferences, and recovery capacity.
Coach Kai's optimal fat loss triangular strategy
The optimal fat loss strategy involves dietary control to create a deficit, strength training to preserve muscle, and cardio or NEAT to accelerate progress; all three corners are indispensable.
While cardio isn't strictly necessary for weight loss, if you want to maximize your fat loss results, Coach Kai believes the best strategy requires three indispensable elements:
First Corner: Diet Control
The most efficient means of creating a caloric deficit. Reducing intake is often easier to achieve a significant caloric gap than increasing expenditure. This is the foundation of the entire fat loss plan.
Second Corner: Strength Training
Maintains muscle mass and preserves basal metabolic rate. This is the one component that cannot be skipped during fat loss. Without strength training, a caloric deficit might consume your muscle along with fat, making subsequent weight loss increasingly difficult.
Third Corner: Cardio or NEAT
Assists in creating more caloric deficit. This can be intentional cardio training or increasing daily activity levels through NEAT; both are effective. If your training volume is already high and recovery is strained, increasing NEAT activities like walking more or taking stairs is often a smarter choice.
The three corners each serve a specific purpose: diet manages the deficit amount, strength training protects muscle and metabolism, and cardio or NEAT accelerates progress. This is a sustainable and effective fat loss framework that can be maintained long-term.
Three ways to create a caloric deficit: Which one is best for you?
Combining diet and exercise is the least stressful and most sustainable approach, making it the most efficient of the three ways to create a caloric deficit.
If you want to take action now, there are three approaches to choose from:
- Adjust diet only: Eat fewer calories than you burn, without changing exercise habits. Suitable for those with limited time for exercise.
- Increase expenditure only: Keep diet unchanged, and increase TDEE through more exercise or NEAT. Suitable for those whose diet is already relatively clean.
- Combine diet and exercise: Eat a little less, move a little more, meeting halfway on both. Coach Kai believes this is the most efficient, easiest, and most sustainable method among the three. Because it doesn't require excessive dietary restrictions or large amounts of exercise, the overall stress is minimized, and sustainability is maximized.
The principle of weight loss is essentially simple arithmetic, but the real challenge lies in integrating it into your daily life and adhering to it long-term. Choosing a method you can consistently follow is far more important than pursuing the fastest way.
Debunking a common myth: Spot reduction.
The human body cannot spot reduce fat; fat loss is systemic, and the effect of localized exercises on body composition is almost negligible.
The human body cannot spot reduce fat. Fat reduction is systemic; the body decides where to mobilize fat first based on its genetics and hormonal conditions, not based on which area you train.
Doing endless sit-ups won't only shrink your belly, and doing endless squats won't only shrink your thighs. Although a 2017 study found that fat breakdown around a specific muscle group was slightly higher when that group was trained, this effect is so small it's almost negligible—you cannot rely on this effect to change your physique.
Instead of wasting time on localized exercises, focus your energy on a comprehensive plan that includes creating a caloric deficit, consistent strength training, and cardio. This is the truly efficient approach.
Summary: The logic of weight loss is clear; execution is the real challenge.
The principles of weight loss are clear, but long-term execution is difficult; choosing a sustainable approach is far more important than pursuing the fastest method.
Let's summarize today's key points:
- The core principle of weight loss is a caloric deficit; all methods ultimately serve this goal.
- TDEE is composed of BMR, EAT, NEAT, and TEF; understanding it helps you create a caloric deficit from multiple angles.
- Cardio is efficient at burning calories in the moment, but it's just one tool for creating a caloric deficit, not a necessary condition for weight loss.
- Only doing cardio without strength training during fat loss will lead to muscle loss and decreased metabolism, making subsequent fat loss increasingly difficult.
- The core function of strength training during fat loss is to maintain muscle mass and preserve basal metabolic rate, not to burn calories.
- The optimal fat loss strategy involves diet control + strength training + cardio or NEAT; all three are indispensable and serve distinct roles.
- The principles of weight loss are simple, but long-term execution is challenging. Choosing a sustainable method is more important than pursuing the fastest one.
No shortcuts, no magic. This is the essence of hard-core training—returning to basics, long-term thinking.
Frequently Asked Questions
Is cardio necessary for weight loss?
Not necessarily. Cardio is just one tool for creating a caloric deficit. Diet control, strength training, and increasing NEAT can all achieve the same goal. What truly matters is whether a sufficient and sustained caloric deficit can be created, rather than choosing a specific exercise method.
What is the role of strength training during fat loss?
During fat loss, the core function of strength training is not to burn calories, but to maintain muscle mass and preserve the basal metabolic rate. It ensures that in a caloric deficit, you lose true fat, not a mixture of fat and muscle, preventing easier weight regain later.
What is NEAT? Does it help with fat loss?
NEAT (Non-Exercise Activity Thermogenesis) refers to all calorie-burning behaviors in daily life apart from intentional exercise, such as walking to commute, climbing stairs, or doing housework. Since our time for intentional exercise is limited each day, the accumulated calorie expenditure from NEAT can be quite substantial, making it an often-overlooked secret weapon for fat loss.
What problems can arise if I only do cardio and no strength training for fat loss?
If you only do cardio without strength training, muscle can likely be lost along with fat in a caloric deficit. Decreased muscle mass leads to a lower basal metabolic rate, meaning fewer calories burned daily. While effective in the short term, this approach makes long-term fat loss more difficult and prone to weight regain.
Can I spot reduce fat by exercising a specific body part?
No. The human body cannot spot reduce fat; fat loss is systemic, and determined by genetics and hormonal conditions which dictate where fat is mobilized first. Doing endless sit-ups won't only shrink your belly, and doing endless squats won't only shrink your thighs. You should focus your energy on an overall plan that creates a caloric deficit.
The content of this article is excerpted from Coach Kai's YouTube channel videos. Training advice is for reference only; if you experience physical discomfort or pain, please consult a professional doctor or physical therapist.
