What is more important when you want to lose weight? Diet or exercise?
In April 2015, an editorial in the British Medical Journal titled “You cannot outrun a bad diet” seemed to suggest that it is diet that matters, rather than exercise, and that exercise doesn't really help with weight loss. What the authors were saying (in a nutshell) was that just “maintaining a healthy weight” – with our without exercise – does not guarantee health. In fact, 40% of people diagnosed with serious metabolic imbalances usually attributed to obesity, such as high blood pressure, high cholesterol, non-alcoholic fatty liver disease and cardiovascular disease, have a ‘normal’ BMI. As explained on this blog before, nutrition is a lot more complicated than “calories in must not exceed calories out”. What matters is where those calories come from. So, the editorial was not saying: “Don’t bother to exercise, it’s not going to make much of a difference” (it’s not in terms of weight loss, but it is in terms of overall health), but “Don’t think that just because you exercise and burn enough calories you’ll be healthy.”
Yes, you can of course lose weight without exercising. You can even lose a lot of weight without exercising … but it’s risky. First of all, you may compromise your bone density. Obese people tend to have stronger bones and 20% higher mineral content, which puts them at a lower risk of bone fractures as they age. Weight loss – and particularly rapid weight loss – can affect bone density very quickly and contribute to mineral loss. To protect your bones, you need to exercise as you lose weight.
Another issue is the problem of a slowed down metabolism. When you are losing weight, you are likely to lose muscle, too. (It is very hard to lose weight and not lose muscle as well.*). Unlike fat cells, muscle cells burn energy even at rest, thus increasing your resting metabolic rate (RMR). Losing muscle means a slower RMR, ie you are burning fewer calories at rest than before. In order to maintain or increase your RMR, you will need to preserve or rebuild as much muscle as possible, and for that you will need to exercise. Dr Wayne Westcott, professor of exercise science at Quincy College in the US, thinks that just two strength training sessions per week will be sufficient. And more good news: It is never too late to start!
Strength exercise is anything that uses resistance to build muscle, using weights, own body weight or even the resistance of water. Cardio exercise – exercise that raises your heart rate – burns calories while you are doing it. Muscles burn calories while you are sitting down, so don’t dismiss resistance exercise, just because you are not sweating as much – and don’t stop doing cardio, such as walking, cycling, running, and swimming – as it does increase your general fitness and stamina and, yes, muscle mass, too.
The benefits of exercise are much, much wider than just the above. There just isn’t enough room in a single blog entry. Endorphins is another one, apparently: Those are neuropeptides secreted during and/or after exercise that make people feel good. Well, most people, I’ll have to say, as it is something I personally never experienced, and consequently exercise was never one of my favourite things to do. I envy people who experience endorphin secretion after exercise. I just feel good after exercise because I know that I won’t have to go back to the gym for two days. But I do it! Yes, I do, because I’ve read the science and I do experience the benefits (except for endorphins), so I keep going. And actually I think that it is growing on me.
If you want to exercise more, but don’t like it, read tomorrow’s Nutrilicious News, which may have some ideas to help.
* Thomas M Longland, Sara Y Oikawa, Cameron J Mitchell, Michaela C Devries, and Stuart M Phillips. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. American Journal of Clinical Nutrition, January 2016 DOI: 10.3945/ajcn.115.119339