Cardio v weights: Which is better for weight loss?

For cardio: Dr Naras Lapsys, accredited practising dietitian

With respect to weight loss, I have found that many of my clients who choose weights over cardio are often disappointed with their results.

There's no doubt that they change body shape and composition and it's very likely that they lose body fat. So, they look great but the scales tell a different story.

Depending on their body type, some people, especially mesomorphs (people who easily put on muscle) and endomorphs (people who easily put on both muscle and fat) often find that they stay the same weight, or even gain weight, despite their shape improving.They've gained muscle bulk, which explains why the scales haven't shown a loss.

If someone is focused on losing weight and they are investing a lot of effort into exercise, it can be demotivating for them to find that all their efforts have resulted in zero weight loss.

It is probably true that if they have more muscle, they have more metabolically active tissue, which means they should be able to burn off even more fat but they still gain muscle weight and the scales don't deliver the goods!

In the mesomorphs and endomorphs, more cardio and less weights may deliver more weight loss. Yes, these people may lose some muscle mass because they aren't doing the strength exercise, however less muscle means more weight loss.

The time spent doing cardio keeps the heart rate up, which expends kilojoules resulting in weight loss. If the cardio is long enough, then the body will start to burn off more fat, which is always the desirable weight-loss goal. If the cardio is shorter in duration and done in interval form (ie, periods of intense cardio and high heart rate followed by a rest periods), this style of cardio also delivers good fat-loss without significant muscle weight gains.

The overall result is a leaner frame and kilos down on the scales. Remember, when someone wants to lose weight, they want to see the results on the scales and they might not be as happy by seeing a smaller waist, more muscle and the same weight on the scales.

With respect to general health and fitness, some weights and resistance exercise is important to promote bone strengthening and reduced risk of osteoporosis. Outright cardio doesn't really address this so some resistance training is important. Both weight training and cardio increase cardio vascular fitness so both methods improve overall health.

In my opinion, it all boils down to what type of body type you have, what shape you want and what weight you want to be. If it is shape and tone, then more weights and less cardio delivers. If you want to be leaner and to lose weight, then more cardio and less weights.

For weights: Daine McDonald, health and performance coach

Since the early '80s, when Jane Fonda was running around in tights teaching the masses about the benefits of cardio training through aerobics, we have been led to believe this type of training is the best form of exercise for fat loss and overall health.

However this couldn't be further from the truth. Since that time plenty of research has shown that long-term steady state aerobic work can actually be detrimental to your health and fat-loss goals.

A 1993 study examining 15 marathon runners with no previous medical disorders showed that long-term aerobic exercise led to increased serum cortisol levels. In a 1994 study regarding androgen turnover rates during endurance running, the researchers noted that cortisol "Increases in response to maximal and submaximal exercise as well as to anxiety or severe illness." In that study, published in Medicine & Science in Sports & Exercise, blood serum cortisol levels in participants at least doubled after the endurance running event.

So what is cortisol? Cortisol is a catabolic hormone and a low-grade adrenaline released by the adrenal glands when we are put under any form of stress.

Numerous studies have proven the link between imbalanced levels of cortisol and abdominal fat. So one could argue that prolonged bouts of cardio training can actually be detrimental to fat loss in particular around ones midsection. So yes, you could actually be running yourself fat!

The best possible outcome from engaging in a fat loss program based solely on cardio training is that you end up as a "skinny-fat" person. Why? Because you lose "weight" through aerobic work — so muscle and fat — rather than just fat. The objective of your exercise program should not be to lose weight — it should be to lose fat, you do this by lifting weights first and foremost.

If you want to lose fat then you need to invest in some weight training — as the body's ultimate fat burner is muscle. For every 500g of muscle the body gains, 250 extra kilojoules are burned a day.

If you increase your lean body mass, you increase your metabolic rate, which in return makes it easier to lose fat. The key to this is through manipulating your weight training loading parameters to increase the body's growth hormone response. GH is an anabolic hormone produced naturally in the body, which helps us regulate body fat.

So for fat loss and optimal health, while some cardiovascular training does have its place, weight training should be the first weapon in your arsenal when it comes to melting away the fat — contrary to popular belief.

What do you think of their arguments? Have your say below!