Do we need to do exercise to lose weight?
I have been motivated to write this blog having spent a few weeks further reading into dietary advice and the history of how dietary advice has changed and developed. It has proved a bit tricky as it has challenged much of what I have believed to be true. The idea that calories in = calories out seemed so simple and balanced that it must be true. I should have known better. As ever – if it seems too good to be true, maybe it is. This is summary of what I have learned.
The last 50 years has seen the development of a huge fitness industry, to make exercise more accessible to a wider range of people. It has been successful and more people appear to be doing regular exercise. It has also seen an increasing obesity crisis – so what is going on? Historically expert food advice came from your mother and your grandmother. Exercise was an essential part of your working day, not an extra luxury for the evening or the weekend, and we didn’t have an obesity crisis. However, people did die earlier in life of respiratory or gastric disease. As medical expertise managed these illnesses more effectively and people lived longer, it appeared that we developed a cardiac disease epidemic.
As a result governments particularly in the USA began to demand more and more expert advice. Dietary models developed and changed and people began to get their expert advice from the state, not their grandma. To make it simple enough for people to understand there was a move to focus on calories and what was considered a base line of an ideal caloric intake. As the obesity crisis developed it became an obvious and easily understandable equation that calories in = calories out, which has simplified the food debate. People were simply eating too much food and consuming too many calories. To control your weight simply requires you to balance the equation which offers you 2 simple options.
1- Do more exercise = burn more calories
2- Eat less food = consume less calories
This seems like a very logical piece of advice, but the obesity crisis continues and if anything it continues to accelerate; so what is going wrong?
My research and reading has led me to the conclusion that both these options and the calories in / out equation are based on poor science and therefore has not been effective and the obesity crisis continues to rise. The false science is this:
Option 1 – Doing more exercise eventually means more fuel is required and the body demands more food and more calories.
Option 2- Reduce calorie intake and the body will subsequently reduce activity.
It under estimates the bodies incredible power to maintain homeostasis. Many invisible functions of the body require fuel/calories every day such as digestion, tissue repair, temperature control, brain function. These will all decrease in line with a decreased fuel intake.
The body has many levels of control to maintain balance in all bodily systems. The gut, liver, pancreas, kidneys and the brain are constantly monitoring intake and output to maintain the perfect balance; Homeostasis.
So we have to change the equation, it is not as simple as calories in=calories out. It is all about the fuel, what the calories are made up of and how the body will respond to them. 1 calorie of olive is different to 1 calorie of sugar. The hormonal response to different substances is varied and whether the body decides to burn the calorie or to store it.
Risking an oversimplification an intake of sugar will stimulate a cascade of insulin and conversion to fat storage. The intake of fat and protein will be broken down into amino acids and energy and used for energy or passed through the system. So we can manage our weight by controlling the type of fuel we consume and worry less about the amount we consume.
So what about exercise, is it part of the equation? The answer is that exercise is important for good health and well being but only accountable for 5% of the daily energy used. Exercise of any kind, from low intensity to high intensity is good for you and makes us move. Movement is essential for joint health and soft tissue health. Exercise will also stimulate gut health and mobilise the gut system. Exercise will train the heart to be an effective and strong muscle and will help to maintain cardiovascular health and circulatory health. Exercise can stimulate and help manage sugar levels in the blood stream. It will also stimulate muscle growth and bone growth. It has been proven to be good for mental health. For all these reasons we should encourage and do more exercise; but for weight loss – not really!
Lower intensity exercises at a heart rate of 180 minus age has been shown to encourage the use of body fat as its primary fuel, where higher intensity exercise with higher heart rates will burn sugar. So exercise will have a contributory effect on weight loss, but probably much less than the simple calories in= calories out would suggest.
For further information read Dr Timothy Noakes, Dr Jason Fung, Mark Sisson or Dr Phil Maffetone.
So what happens when we reduce our calorie intake? Typical advice would be to reduce calorie intake from 2000kcal to 1500kcal – which sounds fair enough. But what the body will also do is reduce its metabolic function by a similar amount. It has to, otherwise we would simply lose weight until we weighed nothing. Subsequently the body shows all the signs of reduced energy intake:
- Reduced Brain function- tired and irritable
- Reduced Body temperature- feeling cold
- Less Energy- less desire to exercise
- Poor Repair- poor nails and hair loss.
Yes, there will initially be some weight loss as the body uses up fat stores to compensate, but this will plateau and you will become tired, grumpy and less energised. You may see some physical changes – poor skin, poor nails or hair loss. A strong willed individual might tolerate this for a year, maybe, but eventually it is not an acceptable feeling so calorie intake will return to 2000kcal. The body, by this time, will have adapted to 1500kcal so the excess calorie intake will now be stored as fat and the original weight returns – plus some. Possibly more damaging is now the person sees themselves as weak and having failed. Subconsciously, society reminds them that they were too weak to succeed and they are worse off than when they started. It does not work! Exercise only accounts for 5% of energy expended so it has little influence on weight loss. If I was being cynical I would argue that the diet industry knows this and locks people into a cycle of weight loss and subsequent gain, rather than educate people to take responsibility to learn and understand how to control weight in a sustainable way. Government / expert advice, however, does not have any excuse. They should be shouting this message from the rooftops, but for some strange reason the message seems to slip out slowly and quietly which makes it look and sound like a fad or the next bit of quackery.
Its time to be honest – the current advice is not working. The evidence is there to change the advice, so lets begin to spread the word. Changing expert advice is difficult. (See Dr Tim Noakes story over the last few years as he took on the authorities in South Africa) He has now been vindicated in court but a less determined person would have been silenced. Experts don’t like saying they are wrong – as they no longer appear to be an expert but this crisis is too important for egos.
For further information read Dr Timothy Noakes, Dr Jason Fung, Mark Sissons or Dr Phil Maffetone.
So, in conclusion to my question.
We do need to do exercise for lots of other reasons – but not in order to lose weight. We need to change the fuel to manage our weight.
I will write next month about fuel and how what we eat has a far more direct effect than how much we eat.
Thanks for reading