Cardio vs strength training: Which one should you be doing to lose weight?

Cardio vs strength training: the eternal question. Even though these are two very different exercises, each with important benefits on their own and together, it's common to wonder if we should be doing one more than the other - especially when it comes to reaching certain health goals like losing weight. 

You may have heard, for instance, that cardio is the winning ingredient to a healthy weight loss journey considering how effective running, cycling, and swimming are at burning calories. Alternatively, you may have heard that strength training offers a superior 'after-burn' effect that burns calories even when you're out of the gym. We're here to separate fact from fiction and reveal if one is better than the other - and why a combination of the two could actually be most effective. 

Of course, the most beneficial exercise will be the one you enjoy the most. As personal trainer Aroosha Nekonam says, "In my experience, those who are the most consistent with their exercise routine are those who have found the exercise they love. So, if you love running, keep running! If you really hate lifting weights, then it's going to be very difficult to maintain that habit long-term," she says. "Doing regular exercise, whether it's cardio or strength training, is always going to be better for you than doing nothing at all." 

But what are the benefits of cardio vs strength training when it comes to weight loss if you're torn between the two? We ask Aroosha and other personal trainers to weigh up the benefits to both to help you design the perfect program for you. Whether you're interested in strength training for weight loss or running for weight loss, here's what you need to know. 

Cardio vs strength training

1. Running burns more calories

To lose weight, you need to be in a calorie deficit. This is where you burn more calories than you consume every day, so naturally exercise (which burns calories) is hugely beneficial. 

Luckily, there's plenty of research that reveals how many calories someone might burn during a workout. Of course, it's all individual, with various factors needing to be taken into account - such as gender, age, and some lifestyle factors - but generally, running burns more calories than strength training. 

The study by Arizona State University reveals that someone weighing 73kg (160lb) is likely to burn around 250 calories per 30 minutes of running at a standard pace, increasing to 365 calories at a faster pace. In comparison, you may only burn between 130 and 220 calories in the gym, which is comparable to the calories you'd burn walking.

So, provided that you choose high-intensity cardio like running, cycling, or doing swimming as a workout, you'll burn more calories with cardio than with strength training.

2. Strength training prevents you from burning muscle as well as fat

Unfortunately, running and long-distance cardio in general is very good for burning calories for weight loss - rather than exclusively fat loss. Weight loss involves every part of the body, including water weight and muscle.

"You’re more likely to start burning through muscle rather than fat with long-term, long-distance cardio," says Nekonam, who works with Ultimate Performance. She explains that those who step up their running routine considerably in one go, without fuelling enough properly, will almost certainly see a drop in their muscle mass. 

That's why strength training is essential alongside any cardio activity, she says. "Strength training encourages the body to retain muscle and tap into fat stores. So, if a leaner, more shapely look is your goal, weights are your friend."

3. Strength training helps you burn calories even after you've left the gym

That's not to say that strength training doesn't help you burn calories at all. As noted, in the session, someone weighing about 73kg could burn up to 220 calories in 30 minutes. Considering that many people spend about an hour working in the gym per session, at the same pace, that's almost 500 calories per session. 

Also, thanks to the positive impact that strength training has on the metabolism, you'll be burning calories long after you've left the gym as it's one of the most effective workouts for building muscle. 

Having more muscle, as research by Columbia University explains, means you will burn more calories when you're resting since your body needs to use more energy to support moving muscle than it does fat. It's for this reason that strength training is known for boosting your metabolism, as your metabolism is what converts the food you eat into energy. With running, the calorie burn lasts until you stop moving.

4. You can eat more and still lose weight with strength training

It may sound counterintuitive to the point about calorie deficits but it's true. "Regular strength training means you can eat more food and still lose weight as you need to feed your muscles to fuel their growth," explains Nekonam.

"If you combine an overly-intense cardio regime with a severely restricted diet, it becomes very hard to sustain. This often leads to a rebound effect where women crave the calories they miss so much they end up eating lots of 'junk' food to satisfy their cravings. If you lift weights, you need to eat more calories to keep your body moving through the session, so at the end of the day, you're eating more but still losing fat. It's a win-win," she says.

5. Strength training for weight loss is better for those going through menopause

For those experiencing menopause symptoms, weight gain is a common complaint. It's a completely natural part of the process, considering the role that hormones like oestrogen play in our bodies. 

“In the peri-menopausal and menopausal periods, the production of hormones - including oestrogen - in the ovaries drops, and fat cells and adrenal glands begin increasing sex hormone production. This can result in losses in muscle mass and bone mass, and if they are inactive, it can ultimately lead to weight gain," says Nekonam. 

If you're looking to avoid menopausal weight gain or lose weight during menopause, strength training will be your answer. "It's been consistently shown to improve insulin sensitivity and glucose control, meaning that the body is better able to process, store and uptake carbohydrates when it needs them, rather than storing them as body fat," she says. "Resistance training also increases a woman’s metabolic rate by increasing fat-free mass, which typically drops after menopause." 

6. Cardio doesn't require as much equipment

With swimming put to the side for a second, in the debate between cardio vs strength training, cardio wins for cost effectiveness most of the time. Most kinds of cardio don't require much equipment compared to strength training where you'll need a gym membership at the bare minimum to get started. Specialists (and us!) also recommend enlisting the help of a personal trainer when you're learning how to start weightlifting as that the activity can be injury prone if your form isn't up to scratch. This is another cost that often outweighs the expense of even a pair of the best running shoes. 

If you're new to exercise, running could be a great way to get a feel for what you enjoy. It's such a fantastic sport for so many reasons but what excites me the most is just how accessible it is," says running coach Ben Parker. "You don't need an expensive gym membership, you don't need a team of people, a pitch or court, all you need is some running trainers most of the time and off you can go."

However, if you're looking to start running as a beginner then it's important to go slowly and avoid the common running mistakes that beginners tend to make - like doing too much too soon.

7. They both have great mental health benefits

While weighing up cardio vs strength training has its uses, there are so many other benefits to both activities aside from weight loss. In fact, if you are looking to lose weight, focusing on these instead of the numbers on the scale could be what makes the difference. 

If you find that spending time in the fresh air does more for your mental health than going to the gym, then more running, walking, and other cardio outdoors will be better suited to you and you're more likely to go. However, you might find that the joint mental and physical challenge of lifting weights boosts your confidence, leaving you feeling sky-high and wanting to get back in the gym the next day.

"We get endorphins from the exercise, we get to experience fresh air, we challenge and push ourselves when we run, leaving us a sense of achievement all of which go to help our mental state and create a sensation often referred to as a 'Runner's high'," says Parker, who is also the founder of Runna, one of the best running apps to use if you're new to the sport. "Plus, no matter how good or how long you run for, there's still a new challenge or personal best around the corner to challenge you."

When it comes to strength training, Nekonam says, "Aside from the physical benefits of having stronger bones, stronger muscles, and a leaner body, the mental and cognitive benefits of knowing you are fit and healthy and don’t have to give in to the aches and pains is incredibly empowering. In fact, a lot of my older female clients tell me that that sense of mental strength gives them a sense of vim and vigour that is even more satisfying than the physical changes to their body."

Can I lose weight by only lifting weights?

Yes, provided you are in a calorie deficit, you can just stick to weightlifting to lose weight. The deficit is all about eating fewer calories than you burn in a day, so provided you have this sorted, you'll lose weight. 

If you are looking to learn how to lose weight without dieting though, incorporating some cardio into a routine would be the best way forward. Some of the best strength training apps can help with this as many offer both cardio and resistance workouts, alongside nutrition plans.

"Cardio or weights is not an ‘either or’ or ‘versus’ situation," explains Nekonam. "Cardio, particularly High Intensity Interval Training (HIIT) can be a very useful complement to a well-structured weight training regime and, when used correctly, can be a very effective tool in accelerating your fat loss efforts." 

Should I do cardio or strength training first? 

Planning on slotting a new-found love for strength training alongside your regular walking workout habit? Parker says that you should lift weights before you hit the treadmill, climb onto the bike, or jump in the pool. "Doing endurance training (i.e. running) before strength can have a negative impact on the strength training performance and the adaptions from it," he explains. "The 'interference effect' is a situation where opposing adaptions are made by our body during both strength training and endurance training. It's why I always recommend doing resistance training first." So, choose your favourite out of the many types of squats and get started.

However, if possible, avoid going immediately from one session to the other. Instead, the coach suggests leaving at least six hours between the two to give your body enough recovery time.