How Effective is Cardio for Weight Loss?
At one point or another, we have all implemented some kind of cardio activity when looking to lose fat. Although rapidly increasing cardio does work to some degree, you need to know when and how to use it to get the best results from it. The goal with any fat loss/body recomposition is to burn fat and maintain muscle (or ideally build some if you’re lucky), so jumping straight into doing a lot of cardio may be more hassle than it’s worth, and in some cases, it can do more harm than good.
The general reason to use cardio throughout a fat loss transformation is to create an energy deficit to encourage body fat to be used as energy, making you leaner. In theory, this means you could just keep doing more and more over the weeks and keep getting leaner and leaner, but there comes a point where it just puts too much stress on the body, wastes muscle away and hinders recovery.
At Ultimate Performance we are lucky if we get 4 hours a week with our clients, and it’s usually 3 – that’s about all most can fit in with their hectic schedules. I’m sure that many of you reading this will be similar. So, if you only have 4 hours (or fewer) a week of training time, then cardio (as it’s less time efficient than resistance training) should be relegated to the bottom of the list, although ideally still included, at least in some capacity. If you can commit to 4 or more sessions then it can be used very effectively without it being excessive. As with everything at Ultimate Performance we look for optimal solutions. So, here are some guidelines to help you make the right choice:
Types of Cardio
Low-intensity steady-state – e.g. walking / MISS – moderate-intensity steady-state (60-70%) e.g. cycling, using the cross trainer
- Great if you’re overweight, as it put less stress on the joints. Also if you are overweight this might be enough to challenge you.
- If you’re training 5-6 times a week your recovery will be limited, and LISS can help create additional energy expenditure without adding too much extra stress which might compromise recovery.
- As above, if you’re performing a lot of lower body training, more stressful forms of cardio might not be appropriate, as they will often tax the legs more than the upper body.
- You can adapt to LISS quickly, and often the only variable you can change is duration; therefore, it is not time efficient.
- If time is limited resistance training should be prioritised over cardio, especially cardio that necessitates a larger time commitment.
- If you are an experienced trainee and are on point with your diet, then chances are walking, although a good addition to your programme, won’t yield significant body composition results.
Short bursts of intense 80-100% effort – e.g. hill sprints
- Positive adaptations include skeletal muscle biogenesis (formation of new mitochondria). Mitochondria generate chemical energy, in the form of a chemical called adenosine triphosphate, or ATP for short. ATP is an energy currency that every cell in our body can use.
- HIIT proves some positive metabolic rate adaptation which other forms of cardio do not provide.
- HIIT has a greater EPOC (Excess post-exercise oxygen consumption) response (post-exercise elevation in metabolism) which means you will burn more calories than you normally would. EPOC increases exponentially with exercise duration.
- HIIT may be too much for beginners to recover from, as it can cause significant stress on the body.
- Performing some types of cardio – sprints for example – may have a great risk of injury, especially for beginners.
- HIIT may limit recovery in the legs between workouts and potentially other body parts depending on what exercises you choose.
Diet vs Cardio
A calorie deficit is paramount for fat loss, and cardio is only a piece of a larger equation. For maximum results in body composition, your top priority should be resistance training, where you have many more variables to manipulate, combined with sticking to a well thought out diet plan. This will set your body up to burn fat and build/retain muscle.
You should be able to monitor progress far more easily through resistance training, making it more apparent when adjustments need to be made. Cardio should merely complement this. Be sure to choose cardio based on your current fitness levels and start slowly, so you have plenty of room for progression.
One of the ways in which cardio can destroy muscle is via elevations of the stress hormone cortisol. Chronic or excessive cardio can lead to excess cortisol. During exercise, cortisol is secreted as soon as a workout starts and continues to rise until completion.
Other than a long list of negative health consequences (altered immune function, cognitive decline, damaged reproductive health, bone loss, etc.), excess cortisol promotes fat storage and muscle loss, partially because it inhibits testosterone, and creates a poor testosterone-to-cortisol (T:C) ratio.
A high T:C ratio is anabolic (tissue-building), while a low ratio is catabolic (tissue-wasting).
With cortisol increasing steadily throughout a workout and testosterone peaking at 20-30 minutes, an unfavourable T:C ratio can be experienced during lengthy exercise bouts. This can leave those training for marathons and triathlons in a chronic muscle-wasting state, with those who think endless cardio will get them in shape not far behind!
How To Apply Cardio Correctly
- Get your diet and resistance training plan in place first; you should stick to this for a minimum of 1-2 weeks without any cardio to ascertain how much, or even whether, you actually need to implement it.
- Depending on your calorie intake, if fat loss stalls you can consider adding cardio in, remembering to keep it simple. With cardio, a general rule of thumb is to do the minimum (not the maximum) that is necessary to achieve the desired result; give yourself somewhere to go as your fat loss journey progresses.
- Pick cardio methods based on your current fitness levels. For example, an overweight beginner may need, to begin with, cycling for 20 minutes three times a week before attempting to hit the Prowler for sets of 10 sprints.
- Make sure that when you choose to do cardio it does not interfere with your resistance training sessions. For example, doing a HIIT workout the day before and after a leg session will limit the recovery in the lower body, which in turn can halt progress.
Progress in weights room is a top priority, never forget that.
Keep a log of what you do (both diet and exercise) to see if the changes you implement are working.
Remember, there is no such thing as a universal, ‘one size fits all’ best cardio workout. The best one for you is the one that challenges you, does not interfere with your resistance training, and most importantly allows you to progress.