Thursday, 16 January 2014

Exercise and Weight

Exercise and Weight

It’s the start of a new year and as always, the start of New Year’s resolutions. The evidence of this can be found quite easily in my gym, which has gone from being pleasantly busy when I arrive after work, to resembling a mosh pit of sweaty, lycra-clad exercisers, jostling for position in the queue for the treadmills.

Despite my exasperation at having to fight for my turn on the cross-trainer, fair play to the New Year’s Resolution crew – regular exercise is one of the most beneficial things you can do for your health and wellbeing.

The benefits of being active are far-reaching, extending to cardiovascular, respiratory, joint and mental health, as well as any other physiological system you care to mention. The simple fact is that the body is designed to be active, and sedentary lifestyles can be linked with all manner of ailments. If we don’t use our bodies, they begin to lose their capacity to be used. The joints cease up, bone density decreases, the muscles weaken (including the heart), resting heart rate and blood pressure increase, lung function is reduced, the immune system is less robust… All possible consequences of an inactive lifestyle.

Unfortunately, the New Year inspired enthusiasm that’s currently clogging up my gym (not that I own it…) will not last. Many of these people will have reverted to a more sedentary way of life before January is out.

One reason for this may be the lack of results that people see. Weight loss is high on the list of reasons why people take up exercise in the first place, and one of the easiest ways of ‘seeing’ results from exercising. But alas, many of the goals people set themselves are not realistic, leading people to give up, disheartened with the lack of results.   

So why is it that exercise doesn’t produce the weight loss we think (or hope!) it should? There are several reasons

1.      Our appetite increases

Appetite is a tricky thing. It’s a very complex mechanism influenced by hormones, genes, the nervous system, fat cells, psychology, the environment... Some people find that their appetite is suppressed by high intensity exercise, others find it increases. Others still find it varies depending on what exercise they’ve been doing (running, swimming, cycling, etc.) and on the conditions (temperature, humidity, etc.) they’ve been exercising in. So as you can see, there’s nothing simple about appetite and exercise!

For those who do find that exercise increases their appetite, it can be difficult resisting the urge to eat more after a session, be it at gym, running in the great outdoors or friendly game of football with your friends. If you know this is going to be an issue, plan your day so that you have a snack or meal timed to coincide with the peak in appetite. This way you can avoid extras but still satisfy the desire for food.

2.   We're not exercising consistently

Consistency is essential if you want to get the most out of exercise. A Sunday morning 10 mile run is all well and good, but if that's followed by a week of nothing more strenuous than climbing the stairs to bed, then a bit of common sense tells you that's probably not going to make much of a difference to your weight in either the short or the long term. Exercise needs to be consistent. It needs to be built in to your daily routine, and it needs to be something you enjoy, or be honest - you're simply not going to want to keep doing it. 

3.    We feel as though we’ve ‘earned’ more food

Exercise should not be about earning food. If one of your reasons for exercising is to lose weight, then you need to make the most of the energy deficit that exercise can contribute to and DON’T eat back the calories you’ve used exercising. Thirty minutes running, or 20 lengths in the pool does not automatically entitle you to a cappuccino and a muffin, unless you want to undo all of that hard work. The exercise will still have its health benefits but as far as calories are concerned, think twice before reaching for the biscuit ‘because you’ve earned it’.

 4.      We overestimate ‘the calorie burn’

All movement requires energy. The higher the intensity and the longer duration, the higher these requirements are. Measuring these calories outside of a research facility is rather difficult, and a variety of formulae are used to estimate the energy demand of an activity. Gym machines like to display calories used, as do various pieces of kit such as heart rate monitors, GPS watches and so on. The accuracy of these is always slightly questionable, and it’s important to see these figures for what they are – an estimate. The more information you are able to program in (age, sex, weight, fitness level, etc.) the more truthful this estimate will be, but it’s not likely to be correct down to the very last calorie. And more importantly than that, the calorie estimate is usually looking at gross calories rather than net.

Gross calories are the total number of calories used during an activity. This includes the calories needed to perform the activity, AND the calories that your body would be using anyway – the energy that is used to keep your heart beating, your blood circulating and your brain functioning: the energy needed to keep you alive, also known as the basal metabolic rate (BMR).

Net calories are those that you use to perform an activity, excluding the calories used for the BMR.

Why does this matter? Because we get fixated on calories, and the difference between gross and net does impact on the rate of weight loss.  

Let’s use an example.

A 30 year old, 5’4”, 70kg woman wants to lose weight. She maintains her diet to a level that would usually keep her weight stable, but starts running on a treadmill for 60 minutes every day. The display on the machine tells her that each session uses 500kcal. She does this every day, accumulating a 3500kcal burn over the week. This should, using the old equation of 3500kcal per pound of fat, result in 1lb of weight loss per week.

However – the 500kcal estimate is gross calorie burn. This includes the calories her body would be using regardless of exercise. Her net calorie burn is 500 – BMR.

The BMR varies from person to person, as it is relative to age, height, weight and sex. For our 70kg lady her BMR is ~1500kcal. Therefore, her energy requirements for BMR are 62.5kcal per hour, regardless of exercise. So her NET calorie burn is 500kcal (from one hour of running) minus 62.5kcal, leaving 437.5kcal. After a week, she will have used just over 3000kcal through exercising – not quite enough to see a one pound weight loss.

Now it is important to remember that our lady should lose weight following a regime like this. But not as rapidly as she might think. And this can lead some to becoming disheartened. Her weight loss is also dependent on her dietary intake – losing weight through exercise alone relies heavily on a carefully controlled diet. And this leads onto our next point.

5. You can’t out-train a bad diet

There’s a certain sense of entitlement that people can feel when they exercise regularly, which links back to point #2 – earning food. This can become more of a persistent problem whereby all dietary restraint is lost and people assume that they can eat freely, as the exercise will take care of any excess calories.

Now let’s think about this.

It’s very, very easy to overeat. Not just the volume of food, but more so the calories. An extra few calories here and there (half a slice of bread, a slightly thicker spreading of butter, an extra splash of gravy, another piece of fruit, etc.) will start to make an appreciable dent into any calorie deficit you might achieve through exercise.

If you start adding in snacks, the dent gets bigger. One digestive biscuit contains 70kcal, and do you really have just the one? A standard packet of crisps is around 180kcal, with the ‘light’ option being around 100kcal. If you’re anything like me, you’ve still got chocolates lingering from Christmas. One Quality Street chocolate is around 40kcal, and again – would you have just one? And as for takeaways - just one per week can rack up a 1000kcal easily, obviously dependant on what you have. That one meal - tasty though it may be - can single-handedly destroy any energy deficit you might have generated. Small snacks, picking at extras, once-in-a-while treats, and slightly larger portions will very quickly sabotage an otherwise healthy diet.

And let’s not forget drinks – a large latte made with whole milk contains a whopping 340 kcals, a can of Coke contains 140kcal, and a 200ml glass of orange juice contains 90kcal. So if you were to have a glass of OJ with breakfast, a mid-morning latte and a can of Coke with lunch you’d have consumed 570kcal – without chewing on a single piece of food. Top tip – don’t drink your calories! If you are thirsty you need to hydrate, not fuel. Keep your energy consumption to meals, not drinks.

If you are like most people, you simply don’t have the time (or perhaps the inclination) to spend hours per day exercising. And if you have a sedentary job, drive to and from work, and enjoy relaxing on the sofa once you’re home, then it’s quite likely that you spend most of your waking hours being inactive. An hour of vigorous exercise simply isn’t enough to make up for 23 hours sitting and a bad (poor quality, energy dense) diet. A more active commute to/from work will help, but still won’t guarantee an energy deficit from exercise.

The simple fact is it is much easier and quicker to consume calories than it is to expend them through exercise. Our 70kg lady would have to cycle at 12mph for 30 minutes to expend 280kcal, the same calories as in a Bounty or a small (50g) bag of dry roasted peanuts – which take far less than 30 minutes to eat.

Unless you spend multiple hours per day training, it is nigh on impossible to out-train a bad diet.

And putting weight to one side, a healthy, balanced diet is essential to good health, longevity and wellbeing. The risks of cardiovascular disease, type 2 diabetes, hypertension, stroke, cancer, etc. are closely linked to dietary intake, and a menu of refined carbohydrates, low quality meats, hydrogenated and trans fats (common in pastries, biscuits, etc.) and sugar is going to take its toll on your health, irrespective of time spent exercising.

Putting all of these factors together you can hopefully see why exercising for the purposes of weight loss isn’t necessarily as easy as it seemingly should be. We overestimate how many calories we’ve used, we eat them back (and then some!), we lose focus from what we’re eating and over-rely on the exercise to compensate for a less than ideal diet.   

As I’ve already said, exercise is one of THE BEST ways of improving your health and wellbeing. There is nothing in the world of medicine and science that can offer the same benefits as regular exercise. 

You can reduce your risk of a whole host of diseases that are associated with sedentary lifestyles, BUT you still need to pay attention to what you are eating. Exercise can improve practically any aspect of your wellbeing – it strengthens your bones, muscles, cardiovascular system, immune function, and respiratory system, it can improve mood, self-esteem, and confidence. Exercise can help with depression, arthritis, diabetes control, and lower blood pressure and cholesterol. And whilst it may not be a magic bullet where weight loss is concerned, it certainly plays a part. Just be realistic in your expectations, and don’t forget all of the other benefits besides what the scales say – after all, your health and wellbeing is about more than your weight. 

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