TL;DR
- Lower intensity exercise burns a higher percentage of fat than high intensity exercise. This is because burning fat requires oxygen (so we need to maintain control of our breath).
- Lower intensity exercises are exercises that are still strenuous but where we can maintain a conversation. Jogging, speed walking, walking up hills, biking, or swimming can be examples.
- High intensity exercise burns calories faster than low intensity exercise, however. Those calories just come more from carbs than fat.
- If you can choose between an hour of speed walking and 25 minutes of running (which will burn similar amounts of calories), the walk will burn a higher percentage of fat. If you have a limited amount of time, the high intensity exercise will tend to burn more fat in the end.
- Muscle also helps burn fat so incorporating strength training is important.
- A mix of low intensity exercise and strength training will be a great option for many people (see below for a training plan from NASM), especially beginners.
- Always consult with a doctor before starting a new fitness routine.
Burning Fat Is Important, But Careful About Making It a Main Motivation
I want to start this post out by saying that I think you’re perfect and amazing at any weight. I hope you’re here because you are curious about how to burn fat. Or because you want to take charge of your health. Not because you are feeling any kind of self-hatred. If it’s the latter, I recommend you take a look at my post on sizeism before delving into this.
I also want to distinguish between losing fat and losing weight. As we workout more, we gain muscle, which can offset the weight of fat loss. This can mean that even as we’re getting healthier, we’re not necessarily losing weight. Plus, as I’ll describe below, some kinds of fat are more unhealthy than others. One person who weighs less than another may have more health risks because of their body composition.
On top of that, some medical and genetic conditions correspond with weight gain, which can make losing weight much harder for some people.
For this and many other reasons, I hesitate to ever talk about fitness in conjunction with losing weight. As I discuss in my post on finding a workout routine you love, losing weight is not a very sustainable motivation for starting a workout routine.
Sustainable Workout Motivations
Instead, the most important things in life make for the best workout motivations. For example, you can find great, sustainable motivations for exercise by thinking about your family, longevity, and passions.
So instead of focusing on losing weight, you might focus on having more energy, improving your mental health, or lowering your risk of certain health conditions. Indeed, exercise can be a great way of lowering your risk of heart disease, regulating high blood pressure, and managing blood sugar levels (thereby lowering the risk of diabetes).
So I recommend finding a motivation that is meaningful to you. Weight loss (and more importantly, sustainable fat loss) will likely follow with a long-term commitment to regular physical activity.
How Our Bodies Burn Fat
So now that you’ve hopefully found a motivation that excites and empowers you, we can turn back to what happens to fat when we exercise. How does our body actually burn fat?
At a very basic level, it has to do with our energy expenditure. Fat cells store energy for use later. When we are active, our body sends that energy to our muscles and organs. When our calorie intake increases without a corresponding increase in activity, our body increases the number and/or size of fat cells to store that extra energy. This is how we can end up with too much body fat, also called adipose tissue.
Having too much body fat can be a problem for a variety of reasons. One of them is that body fat releases hormones that communicate with other parts of our body. When we have too much body fat, those hormones get out of whack and can send our body spiraling.
Moreover, not all fat is created equal. Visceral fat is the fat that surrounds our organs. Having visceral belly fat is the type of fat that most corresponds with health risks like diabetes and heart disease. Consequently, it’s the type of fat we most want to prevent and work on.
The good news is that once we get into a habit of exercising and maintaining a moderate diet, our body starts retaining less fat. In fact, it starts sending energy directly to muscles and organs rather than retaining it. This is how our metabolic rate increases and our body composition changes.
How Exercise Can Burn Fat
The best type of exercise for burning fat is probably not what you would expect. If I told you to guess the best exercises for burning fat, you’d probably tell me something really intense: hard running, endless burpees, anything that feels like your body is literally on fire and you maybe want to barf a little.
What if I told you one of the best exercises is *drumroll* walking? Please, hold your applause. I know that’s pretty incredible news that something as simple and not that horrible as walking is one of the best tools for burning fat. And I’m actually telling the truth.
It all has to do with how energy is used during exercise. When we workout really hard, our bodies rely primarily on carbohydrates to produce energy. However, when we workout at a more moderate level, our bodies primarily rely on fat for energy production.
If you want to get technical, the reason is that your body needs oxygen to burn fat. You literally exhale fat! Or at least, you exhale the fat leftovers after you’ve used the energy in fat. So weird, right? If you are out of breath, your body isn’t getting as much oxygen to burn fat.
Plus, your body can burn carbs for energy faster than it can burn fat. Consequently, if your body is scrambling to produce energy, it will start relying on carbs. Usually your body burns a mix of carbs and fat. Though if you’re working out super intensely, there can come a point where your body is burning almost entirely carbs.
Exercises That Help You Burn Fat
This is why exercises that are low enough intensity for you to maintain your breath (like walking!) are the best way of burning fat for a given level of energy. The key is to workout at a level that still feels somewhat strenuous. For example, you are probably breathing heavier than normal and sweating. However, you can hold a conversation (a signal that you are still maintaining control of your breath).
Cardiovascular exercise and aerobic exercise are especially good for getting you in that zone. Depending on your fitness level and interests, some exercises that could help you hit that fat burner zone are: jogging at a moderate pace, stationary biking, swimming, dancing, fast walking, walking up hills, or walking with weights. What counts as fast walking will also vary depending on where you’re at in your fitness journey. Consequently, don’t get discouraged if your fast walking pace differs from others.
If you have a fitness tracker, you might monitor your heart rate to help you figure out when you’re in the fat burner zone. You are in your fat burner zone if you are working out at 70% of your max heart rate. An easy way to gauge your max heart rate is to subtract your age from 220. That will give you a rough approximation of your max heart rate.
The Caveat: High Intensity Exercise Burns More Calories
However, there is a caveat to the importance of lower intensity exercise for fat burning. High intensity exercises burn more calories for a given amount of time than lower intensity exercises. You might be getting confused here. Didn’t I just say that for a given level of energy low-intensity exercises burn more fat than high-intensity exercises? The operative phrase is “for a given level of energy.” For example, I burn just as many calories from a 25 minute hard run as I do from a 1-hour walk. They use the same amount of energy, but the walk will tend to burn more fat.
Consequently, if I only had 25 minutes to exercise, I’d be better off with the high-intensity run. The greater calorie burn of the run will lead to more burned fat. However, if I could choose between a 25 minute hard run and an hour walk, the hour walk will burn more fat.
Indeed, some research has found that high-intensity interval training (HIIT), which involves big bursts of energy interspersed with short breaks, is the fastest way of getting a good calorie burn. And HIIT causes your body to burn calories for up to 24 hours after your workout. As a result, some articles have pointed out that the greater efficiency of high intensity exercise means it’s better for burning fat.
However, high intensity exercise is still a biologically less efficient option than lower intensity exercise. Moreover, for many people, especially those new to exercise or who don’t enjoy high intensity exercise, going for an hour walk will sound way better than 25 minutes of high intensity interval training.
Burn Fat Over Time: The Role of Muscle Building
Another important mechanism for achieving a healthy weight is adding muscle mass. Muscle helps rev up our metabolism for up to 24 hours after exercise. A recent study found that muscle sends genetic material to fat cells that basically spur them to move to a fat burning phase.
Plus, muscle weighs more than fat and greater body weight requires our body to exert more energy and so burn more fat.
Consequently, weight training or resistance training has lots of health benefits.
If you are worried about adding bulk, don’t be. To have body builder muscles you would need to lift heavy weights for hours every day and fundamentally change your diet. Rather, if you start lifting weights regularly, your arms might approach Michelle Obama level. There’s approximately 0 percent chance they’d come anything close to WWE level. Being a bodybuilder wouldn’t be a profession if it happened accidentally after all.
Okay, So What Should I Actually Do to Burn Fat
Consequently, if you have time for it, an exercise plan that includes a mix of low to moderate intensity cardiovascular exercises and weight training will give you the most fat-burning bang for your energy buck and is a great place to start for beginners.
If you have a limited amount of time (like 30 minutes or less per day), enjoy high intensity exercise enough to stick with it, and have been working out consistently enough to safely progress to high intensity exercise, then high intensity exercise will be more efficient for fat burning. However, again, make sure you work up to high intensity exercise and consult your doctor before starting a new routine, it’s dangerous to jump into high intensity work if you haven’t been working out consistently.
You might also start by looking for a class or personal trainer that can help safely instruct you in HIIT or other exercises.
Exercise Plan Examples
I started my fitness journey by doing 30 minutes of moderate intensity cardio like walking, hiking, jogging, swimming or biking 5 days a week. I also added in 10 minutes of resistance training 6 days a week (2 days for lower body, 2 days for upper body, and 2 days for core). For a moderate activity level, this is a great start for burning abdominal fat. However, it’s perfectly understandable and still effective to work out less or more depending on your time and interests.
You can check out my posts on 10-minute workouts for beginners and strength training workouts without dumbbells for ideas.
Women’s Health Magazine also has an article with a nice mix of HIIT workouts depending on the time you can devote. And Men’s Health magazine has some good options. Ignore the gendered nature of these publications, you could follow either magazines recommendations to get results regardless of your gender.
If you want a more structured recommendation, National Academy of Sports Medicine (NASM) is generally considered one of the most reputable organizations for personal trainer certifications and they have a great 5-week workout plan for beginners.
The Role of Diet in Fat Burning
Regular physical activity is so important for improving your health. However, individuals who start a workout routine frequently make the mistake of overestimating the amount of calories they burn from exercise. As a result, many people end up over-consuming calories later and negating the calorie and fat burning benefits of exercise. Consequently, for best results, it’s a good idea to balance exercise with a balanced diet to achieve a healthy weight.
On a broad level, you’ll want to be somewhat mindful of your caloric intake. To lose weight, you need to burn a higher number of calories from activity than you’re taking in. This is called having a calorie deficit.
While that’s not exactly a fun proposition, there are some foods that make this easier. Specifically, diets high in protein, fiber, and healthy fats can keep you full and nourished.
The Role of Fiber in Fat-Burning
Soluble fiber is great for our health. It’s not digestible by the body, so it fills us up without being retained. Additionally, fiber helps feed the good bacteria in our body, cultivating a healthy digestive tract. This is also one of the reasons that a low-carb diet is not really your best friend when it comes to fat burning and health.
Good sources of fiber include whole grains (like quinoa, brown rice, oats, corn, whole wheat, barley, and rye), fruit, and vegetables.
The Counter-Intuitive Relationship between Eating Fat and Burning Fat
For a long time, people thought that a low-fat diet was the key to burning fat. It makes sense intuitively, but doesn’t work well in practice. Healthy fats like polyunsaturated fats (e.g. Omega-3 fatty acids) and monounsaturated fats help keep us full and so prevent overeating. Plus, increasing our intake of healthy fats can help balance our hormones like estrogen, our hunger hormones ghrelin and leptin, and more. Check out my post on hormone balancing foods if you want more info.
You can find good sources of dietary fat in olive oil, whole fat dairy products, nuts and seeds.
High-Protein High Fat Burning
Like with fiber and healthy fat, a high protein diet helps keep us full. Protein is also made up of the building blocks that create our muscles. It’s therefore important for muscle-buliding.
Protein-rich foods include beans, nuts, tofu, eggs, and lean cuts of meat. For example, turkey and chicken are good lean protein sources.
Things to Avoid
And finally, there are a few things you should avoid. For one, sugar is a big culprit in adding fat. This is especially the case for refined sugar. The sugar that you find in fruits and whole foods digests more slowly than refined sugar. Reducing your intake of sugary drinks, desserts, and even sugary sauces like ketchup, can help. Artificial sugars are also not great. They throw off your hormone balance and can lead to weight gain and other health issues.
Second, avoid fad diets that promote entirely including or excluding one nutrient group. Our bodies need a range of nutrients to function and produce energy. Unless you have an allergy or intolerance, there’s little reason to eliminate entire food groups from your diet for health reasons.
Finally, be mindful of fat-burning supplements. The most important thing is to consult with a doctor about these supplements. However, they can have severe side effects like liver failure and high blood pressure. Consequently, many experts recommend starting with exercise and diet before moving to these options.
The Role of Sleep in Fat Burning
In addition to diet and exercise, it’s important to get enough sleep. Most of us should aim for 7-9 hours of sleep each night. Sleep deprivation means that your energy levels will be low, making it harder to exercise. Sleep deprivation also increases your risk of injury because sleep is when our muscles repair and recover.
Plus, sleep itself promotes weight loss. Indeed, when we stay up late, we experience an increase in our hunger-promoting hormone ghrelin. This can cause us to eat more (and more unhealthy) food.
If you’re like me and struggle with sleep on occasion, feel free to check out my post on tips for insomnia.
Consequently, for best results, you should combine a workout plan you enjoy with a balanced diet and sleep.
Final Thoughts
The bottom line is that the workout routine that will lead to the most fat burned is the one you stick with and do consistently. So even if you don’t have much time and high intensity exercise sounds horrible, go for a walk! A walk is an amazing workout. If that still sounds horrible, find a friend to suffer with you, go on a hike in a beautiful spot (see my recommendations for getting started with hiking), sign up for a class that sounds fun, or just crank up the music and dance around your house.
And to get the most bang for your buck, make sure you’re eating a balance diet and giving yourself time to rest. Full disclosure, my balanced diet still includes a decent amount of chocolate. Like with exercise, balance and something you can stick with is the key.
Last but not least, keep in mind that I am not a certified personal trainer or a medical professional. Make sure to consult with a professional before starting a new fitness plan.
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