Cardio VS Weight Training: Which is better for Fat Loss?

If you’re looking to drop fat, I’m sure you’ve considered whether cardio or weight training will get the results you seek. 

It’s a great debate that continues to roar. On one side, you’ve got the cardio crusaders fearing weights could make them too muscly or too bulky. And on the other, you’ve got the weekend warriors who believe cardio will sabotage their results and undo their gains #SkinnyFat. 

The one truth both parties share is the most effective way to lose fat is to burn more calories than you consume. Yet, this is also the basis for the divide. Both cardio and weight training do burn calories, but differently. Cardio burns more calories in the workout itself, while strength training burns more calories after that workout.

Want to know where you should spend your energy? Read on, as we go beyond the myths to uncover what’s best to achieve your goals. 

The Simple Science of Fat Loss

Before we discover what’s best for fat loss, it’s important to understand the basics of how fat loss occurs. For this we’ll start with calories which is a unit of measurement for energy. The energy in the food we eat and the movement we do is measured in calories. 

Put simply, you cannot lose weight without burning more energy than you take in. The opposite is also true, you cannot gain weight unless you consume more energy than you burn. Fat is excess energy stored in the body and if your goal is to lose it, and I’m assuming that’s why you are here, then understanding how we can burn more calories seems like a natural next step. 

Cardio burns more calories during the workout

There’s a lot of research and even more opinions on whether weight training or cardio burns more calories. A recent Harvard Study in March 2021 considered the calories burned from various activities in 30 minutes by a 70.3kg person. 

When doing cardio the person burned 360 calories running at a moderate pace (6.2 Min/KM). Comparatively, they burned 216 calories Weight Lifting vigorously. As this study and others have shown, cardio does burn more calories than weight focused training during the workout when training at a relative effort. Source: Harvard Health Publishing

Cardio can certainly help you lose weight with more calories burned in the workout but what that weight is made of proves crucially important. With cardio both fat loss and muscle loss has been shown to occur. Source: PubMD

This means that even though you may be losing weight on the scale and getting smaller, you may not be necessarily getting the leaner physique you are after. Fat loss is the goal but losing muscle can be detrimental to your ongoing success. 

Also, with cardio you adapt to the training over time. So even though you burned a sweaty bucket load of calories the first time you got off the couch to run 5 kilometres. Over time the calories burned from the same workout will decrease and you will have to continue to increase the intensity or duration to get the same results you previously achieved with less. 

So even though cardio can help you burn more calories and drop more weight. It also leads to muscle loss and requires increased effort to sustain the changes made.

Weight training burns more calories after the workout 

Cardio is great for burning calories during the workout but weight training helps you burn more calories every day. (Yes - even on rest days!)  

As we’ve shown, a calorie deficit is the most effective way to lose fat but there is some risk of losing muscle if using cardio alone. When we lose muscle our resting metabolic rate goes down and we burn less calories each day. 

Weight training can help you lose fat but also build and retain muscle which helps to keep our resting metabolic rate higher. Your resting metabolic rate accounts to around 70% of the energy you burn while the calories burned in a workout equates to around 5% each day. You can learn more about Total Daily Expenditure. 

This difference shows the importance of prioritising the calories burned beyond the workout rather than in the workout itself. Weight training burns less calories than cardio when working out initially, however you’re able to increase your resting metabolic rate and continue to get an increasing return (calorie burn) for your efforts. You could consider it a rock solid investment in your leanest, strongest self! 

What’s best for fat loss? 

As someone who’s personally dropped 40 kilos and 30% body fat I’ve made it a mission to uncover the facts of fat loss.

While your training is important, the most effective way to lose fat is through an energy deficit and the easiest way to lose fat initially is through better nutrition. I’m sure you’ve heard that ‘you can’t exercise a bad diet’ and you certainly can consume calories much faster than you could ever burn them. 

Like cardio, when dieting the body adapts to a calorie deficit by decreasing the energy burned each day which eventually leads to a fat loss plateau. Your body’s main goal is to stay alive and simply isn’t that interested in your next beach date. When you start dipping into your body's energy stores (fat), the body aims to counteract this with decreased calories burned through lower metabolic rate, digestion and movement. This is known as metabolic adaptation and it’s best to start with a small calorie deficit and avoid very low calorie diets or long periods of dieting to minimise the impacts. 

When in a deficit it’s also very important to get enough protein. The goal is to burn excess energy stored in the body but the main component of muscle, skin, bones, organs and nails is protein. Protein also leads to greater satiety and reduced hunger, making it easier to manage your diet while burning more calories through digestion. 

With nutrition dialled in, your training can help get even better results faster. With this in mind the very literal ‘first step’ to greater fat loss is to start increasing your daily steps with a goal of 10,000 steps per day as a great cardio baseline. Cardio also has the added benefits of cardiovascular health and increased fitness but doesn’t need to be intense. With just a brisk walk you can enjoy better physical and mental well-being - while also reducing your waistline. 

When it comes to the relatively more intense training. I recommend 2-4 weight training sessions per week. This ensures you are not just losing weight but also getting leaner. Weight training optimises hormones, raises metabolic rate and of course builds strength. 

A progressive weight training program is best, where you can build on the weights lifted the week prior with the same or similar movements.This provides the greater stimulus required to build or retain lean muscle while increasing the calories you burn from each workout. 

Keep in mind that cardio and strength training are on different ends of the spectrum. I personally recommend higher intensity strength training that starts with compound lifts and often using supersets. Including a small amount of conditioning after strength in the same workout has also been shown to increase calories burned with a heart rate 12 beats per minute higher over cardio alone due to pre-fatigue from the weight training. Source: Semantic Scholar

This increases the metabolic effect and calories burned while building a leaner, stronger physique. 

Finally, with a solid base of nutrition, daily steps and weight training I would consider adding High Intensity Interval Training (HIIT) or Cardio activities like jogging, running, swimming, cycling or any equivalent depending on the rate of fat loss. With HIIT less is often more and up to 2 sessions per week is ideal for more due to the stress and recovery involved. Cardio can help you burn more calories and drop weight faster and the risk of muscle loss is mitigated when incorporated with weight training. Source: Journal of Applied Physiology 

Key takeaway

What’s most important to consider is the long term results we seek and this needs to go beyond any single workout. As research shows cardio does burn more calories while working out while weight training burns more calories after.

Cardio can help you lose weight faster but you’ll need to continually increase effort to burn the same amount of calories in each workout. It can also be catabolic and lead to muscle loss without the introduction of weight training into your program. 

Weight training helps you lose fat while also building or retaining muscle which keeps your metabolism higher. Unlike cardio, with weight training your efforts are compounded leading to greater results in the relatively longer term. 

With all of the research, personal experience losing 40 kilos and coaching for over 15 years, I believe you should include weight training on a solid base of nutrition habits and daily steps. This will help lose fat, retain muscle and optimise your metabolism. From there additional cardio, conditioning or HIIT can be added to increase the rate of fat lost. 

Now you’ve got the facts, but at the end of the day the best training and nutrition plan for you, is the one you can consistently do.