That daily exercise class won’t make up for hours and hours of sitting still. Indeed, too much resting – even if you are doing regular exercise most days – can have a detrimental affect on your health. Former GP Juliet McGrattan explains.

You want to lose weight and improve your health, so you’ve planned your healthy meals, booked yourself some exercise classes and you’re meeting your friend for a walk, so surely that means you are all set for a healthy week, doesn’t it? But how active are you really? Can you rely on short windows of exercise to help you burn fat and most importantly, maintain your health? Apparently not. There’s one thing that you may have overlooked, something that will improve your health and aid your weight loss. Something so simple but so important.

If you want to boost your health and keep the weight loss consistent, you need to reduce the amount of time you spend sitting around doing nothing. The amount of time you spend sitting has a direct effect on your health, and is now considered almost as serious as smoking. Being regularly active is often overlooked but it’s vital for good health. It’s simply not enough to exercise for half an hour a day and then spend the rest of the day sitting still. If that sounds like a challenge, it’s not as hard as it seems. Let’s look at why it’s important to be on the move as much as possible and what you can do to stay active.

Why do we need to move more?

The Health Survey for England in 2012 reported that over half of men and women in the UK spend at least four hours leading a sedentary lifestyle during the week. This level of inactivity increases at the weekend. Many people sit for more than seven hours a day and we typically tend to sit more as we get older. The current physical activity guidelines from the Chief Medical Officer recommend that we should be doing at least 150 minutes of moderate intensity activity every week, (that’s exercise that makes you feel a bit out of breath), but they also state that we should reduce our sedentary time.

Even if we meet the 150-minute exercise target, there are still risks to our health from spending long periods of time sitting down. Levels of obesity and physical and mental health problems are higher in those who spend more time sitting compared to people who are more active.

This simply means that you can’t rely on that 30-minute exercise class on the way home from work to make you healthy. That blast of exercise doesn’t cancel out the fact that you’ve spent the rest of the day sitting. We don’t yet know exactly how long it’s safe to sit for but you need to look at ways to keep you moving in regular bursts throughout the day to maximise your health.

Why is sitting so bad for us?

Firstly, let’s look at why sitting is so detrimental to our health. Quite simply, our bodies were designed to move. When we sit for a prolonged period, there are changes that occur in our body which have a negative effect on our health and wellbeing.

Firstly, our bodies contain mitochondria – these are the batteries of our cells and they continuously generate energy for our body to use. If we’re sitting still and not using this energy, it builds up in the cells and causes damage which can lead to the cell dying early. This early cell death causes inflammation in the body which we now know is one of the causes of major diseases such as heart disease, cancer and Type 2 diabetes. If we can move on and off throughout the day, then this energy doesn’t accumulate, cells remain healthy and so do we.

Secondly, when we sit, our metabolism is affected in a negative way. Our bodies switch into storage mode. A good example of this is lipoprotein lipase, an important fat burning enzyme, which switches off after about 20 minutes of being sedentary. Another mechanism is the way our body deals with fuel. Insulin is the hormone that regulates our blood sugar and when we eat, it determines how much is used and how much is stored. If our bodies become resistant to insulin, then we are more likely to become obese and develop Type 2 diabetes. (It’s important to know that you can be resistant to insulin without being obese). Moving around for a just a couple of minutes can improve your body’s insulin responses to food. Keeping physically active on and off throughout the day will heighten your sensitivity to insulin and reduce your risk of Type 2 diabetes, cardiovascular disease and cancer.

Why sitting can cause diseases

The other thing that happens when we sit is that we don’t use our muscles. When we use our muscles, they release something called myokines which have an anti-inflammatory action in our body. We’ve discussed how inflammation is responsible for many major diseases, so getting our body’s own source of anti-inflammatories is important. Building and maintaining our muscles and using them frequently will ensure more myokines are circulated. It will also boost our metabolism leading to higher calorie consumption which can aid weight loss if this is our goal.

When we don’t use our muscles, not only do we miss out on the anti-inflammatory action but our muscles become weaker and this can affect our joint health. Having strong muscles surrounding our joints can take pressure off the bones and cartilage within joints, helping to protect against osteoarthritis. Sitting causes our core muscles and glutes to weaken – the glutes are our bottom muscles and are the biggest muscles in the body. Weak core and glutes are a major cause of low back pain. Avoiding prolonged sitting and simply moving more and strengthening these muscles can help to support our spine and prevent back pain.

Weak core and glutes from sitting are also linked to weak pelvic floor muscles in women which may result in urinary incontinence. Prolonged sitting has a negative effect on our bones too and can result in osteoporosis, a condition where bones are weak, fragile and at risk of breaking.

So, while it’s nice to have a sit down every now and then, it’s important to realise that prolonged sitting can have a very negative effect on our health and we should take steps to move frequently on and off throughout the day. Relying on our 30-minutes of activity isn’t enough and simply moving more can help to boost our health, reduce our weight and lower our risk of disease.

The long-term effects of a sedentary lifestyle

 You can be physically active and taking regular exercise but if you spend too long sitting each day, you still have significant health risks. According to the World Health Organisation, 60 to 85 per cent of people in the world lead sedentary lifestyles. A sedentary lifestyle can double your risk of being obese and developing Type 2 diabetes and cardiovascular disease. There are very few systems in the body that won’t be negatively affected by being sedentary. Physical health problems such as high blood pressure, osteoporosis and colon cancer are more common in those with a sedentary lifestyle and importantly, so are mental health problems such as anxiety and depression. There’s growing evidence that a sedentary life can increase your risk of dementia and that by being more active you can reduce your risk of developing it by as much as 30 per cent. It’s never too late to start moving more and reaping the benefits.

Juliet McGrattan is a former GP and author of the book Sorted! The Active Woman’s Guide To Health (Bloomsbury, £11.27).