Cardio or Resistance Training — Which Is Better for Weight Loss?
Cast your mind back ten, maybe fifteen years, it seemed so simple...you did cardio to lose weight and reduce your size, because “cardio burned calories and lifting weights made you bulky”, and you lifted weights to build muscles, because “weights build muscle, whereas cardio burned muscle and reduced your size”. Everyone chose one approach. It was all very black and white (like the TVs at the time).
Fast forward to the modern-day, many scientific studies later, do you think the above statements are correct? Do we still need to pick a side? Or can we obtain the benefits of both?
As much as any exercise is better than no exercise, we all have goals or an endpoint in mind, usually an aesthetic or a performance-related goal. If we really want to hit those goals, we need to train right, we need to train smart, so understanding the impact on our bodies of resistance training, cardio and a combination of the two is vital if we don’t want to spend hours in the gym, or out on the road running, only to get no closer to our aspirations.
Let’s begin by looking at the impact of regular resistance training.
Will weights make me bulky?
No! Excess calories make you bulky.
Many people avoid lifting weight as they fear bulking up, and I’m here to tell you that this is a ludicrous thought process — it’s like opening up a savers account and worrying you’re going to accidentally wake up a millionaire. Most people who lift weights to aid their fat loss journey do so with a calorie-controlled diet, so they don’t get bulky, they get lean.
Resistance training has been proven many times over to have a wealth of benefits; benefits that are conducive to those wanting to lose weight or gain muscle, to maintain their current body composition and improve their overall health markers.
Resistance training benefits
Increased strength
Increased muscle mass
Improved bone strength, as found in a review performed by A Ram Hong and Sang Wan Kim in 2018.
Improved metabolic rate (Resistance Training and Anaerobic Training, along with a high protein diet will grow muscles, these muscles need fuel, that fuel is taken from the calories you consume each day)
Minimise the age-related loss of lean body mass (Sarcopenia)
Can aid sleep
You leave the gym feeling ‘pumped’ — muscles full of blood — feeling jacked
Improved health-related quality of life — this was found to be the case in a recent meta-analysis by Peter D Hart and Diona J Buck.
More than just building muscles, right?
Does Cardio burn muscle?
Ok, so cardio does burn calories, true story. What else does it affect?
Cardio training benefits
Improved the heart and lungs, boosting overall fitness
Reduces risk of stroke, heart disease (as cited in a meta-analysis by Adrian Thorogood et al from the American Journal of Medicine) and diabetes
Can aid sleep
You can’t beat that feeling after a run, a real feeling of accomplishment and lasting feelings of well-being. In fact, a meta-analysis by Ioannis D Morres et al from the Depression and Anxiety Journal found that aerobic exercise emerged as an effective antidepressant intervention.
Once, again, way more than just burning calories. But does it ‘burn muscle’?
Human biology is the source of truth for this age-old question. There are three basic energy systems and regardless of which of these is used, the result is the production of ATP (Adenosine Triphosphate) — your body’s energy currency.
Energy Systems
Long-term (Aerobic system).
Here the body has sufficient oxygen to meet the demands of the activity, such as moderate cardiovascular training, like jogging or cycling. Fat and glucose (carbs) are used as energy sources and protein will be used if all the fats and carbs are diminished.
Short-term (Anaerobic / lactic acid system).
The oxygen demands exceed the oxygen supply, usually high-intensity activities from 10 to 90 seconds, like a 200m to 400m run — this system uses glucose (carbs) for fuel.
Immediate energy (ATP-phosphocreatine system).
This is used for all-out exercise that lasts from 5 to 10 seconds, for example, diving, jumping, or any other activity that involves a maximal, short burst of power. The body uses creatine phosphate stored ATP within the muscles in an instantaneous manner.
ATP is extracted from the food we consume (fat, carbohydrate and protein aka macronutrients) and is required for any muscle contraction. The intensity and duration of the activity dictates which macronutrients are broken down and which energy system predominates, as no energy system acts alone and they do not all extract energy from all macronutrients.
Protein is not a preferred source of energy for any of the energy systems (assuming an adequate diet) and generally contributes less than 10% of the total energy requirements. Your body doesn’t single out cardio and suddenly begin to eat your muscle, it just doesn’t happen. The truth is, you need a sufficient amount of calories and protein in your diet in order to maintain and grow muscles and excessive cardio will consume these calories, potentially creating a calorie deficit which may mean your muscles will reduce in size. If you are eating well, muscles aren’t being burned away as you do your weekly 10k run, if you don’t believe me, see what the Journal of Applied Physiology found during a randomised controlled study by Tommy R. Lundberg. They concluded that Aerobic exercise does not compromise muscle hypertrophy response to short-term resistance training
Should I do cardio and resistance training?
So, we can see that resistance training and cardio exercise both have very many important benefits. Some of these benefits are shared, like weight loss, for example, but some are weighted towards a particular type of training. There is absolutely no reason why the two can’t live together harmoniously within an individual’s training programme. You just need to train smart and prioritise the exercise that is conducive to your goal.
You’ve all seen those Olympic Sprinters, right? They run and they have strong, muscular physiques. You’ve also seen Olympic long-distance runners, right? They run far longer distances, so burn really high levels of calories, they too are in fantastic shape but their muscle size is far smaller.
Both of these types of athletes will be combining cardio and resistance training BUT they will be prioritising appropriately to meet their goals.
If your goal is body composition, lean muscle building, there is no reason for you to cut out your weekly or even bi-weekly runs. They should however be secondary to your resistance training. Lifting heavy weights, regularly, should be your priority and cardio should be either after resistance training or ideally, on a resistance training rest day so you are giving your body time to recover.
If your goal is to run a marathon, then you would prioritise running over the resistance training but don’t underestimate the impact resistance training will have on your run. Your muscles will be stronger and have more endurance which will indeed have a positive impact on your running.
Adding further weight to the combined approach is a recent randomised controlled trial by Elizabeth C Shroeder, where the impact of resistance training, cardio training and a combination of the two were compared in relation to the risk factors of cardiovascular disease (CVD). The findings were that combination training may be of better value than aerobic or resistance training alone, as it appeared to have the most beneficial effect on the composite of CVD risk factors. So, aside from aesthetic or performance improvements, a combined approach also carries weight of health benefits being even greater improved when training is combined.
In summary...
If your ambition is to be the strongest, fittest version of you, giving you good health and longevity, mix up cardio and resistance training within a structured, goal-orientated training programme, incorporate the things you love and just enjoy it. Personally, I follow a combined programme, prioritising resistance training but also getting in some adhoc runs. This not only maintains my muscle and cardiovascular health but importantly, it gives me headspace, time in the great outdoors with just me and the Welsh hills. As much as training should be efficient, focused and smart, we shouldn’t forget that it’s also extremely enjoyable and we should have a training programme that allows us to indulge in the activities that we love!