Exercise and weight loss: everything you need to know
For those who are overweight, the health benefits of losing weight are numerous – and exercise is a great way to improve fitness at the same time.
Being a healthy weight can reduce the risk of heart disease, diabetes, stroke and some cancers, while the endorphins released during exercise can help to boost mood and improve mental health.
Happily, getting fit and active through regular exercise further reduces your risk of heart and circulatory diseases – by lowering your resting blood pressure and heart rate and improving your cholesterol levels. It has lots of other health benefits, too, including improving brain health, strengthening bones and muscles and improving lung capacity.
What are the best exercises for weight loss?
The first thing to understand is that weight loss is simply a mismatch between the amount of energy we consume versus the amount of energy we use. The amount of energy in food or drink is measured in calories.
'Exercise and physical activity help us to expend more energy (calories) in a way that can allow people to achieve weight loss,' says David Rogerson, principal lecturer in sport and exercise science, Sheffield Hallam University. 'Any exercise will facilitate weight loss, and the research supports that. [But] the evidence suggests that aerobic exercise, called moderate intensity continuous training, is just as effective as high intensity interval training.'
Although vigorous workouts, such as a spinning class, HIIT session or running speed intervals, involve a high level of effort, they are usually not carried out for as long as a moderate effort, such as a slow run, so the two forms of exercises can have a comparable impact on weight loss.
But rather than thinking about the intensity, or the type, of exercise, Rogerson recommends choosing an activity that you enjoy which you can incorporate into your lifestyle. 'Think about what you can stick to and be consistent with over a longer period of time. That is generally the best kind of exercise,' he says.
And it can be beneficial to start with something simple like walking, before progressing to running. 'For someone transitioning to exercise from a sedentary lifestyle, I recommend walking,' recommends personal trainer Josh York. 'Walking, generally, is less intense of a workout which means you can gradually build up your cardiovascular fitness to handle a harder workout. If you can find ways to pick up your speed or walk on an incline, you will boost the intensity of your workout over time.'
And if you are beginning a more impactful exercise like running, then complementing it with regular strength training will help to reduce the risk of injury.
How to measure calorie burning during exercise
Ultimately to lose weight you need to burn more calories than you are consuming. This can be done through a combination of diet and exercise.
You can use running and smart watches to help you to track you calorie output during exercise, but Rogerson says there is a simple way to calculate this using the MET approach, which doesn't require any tech.
'This is the metabolic equivalent of a task. One MET represents the amount of calories you burn at rest, when you are doing nothing. If someone weights 75kg they will probably burn 75 calories per hour doing nothing. This number can then be multiplied by the type of exercise someone does,' explains Rogerson.
Bodyweight x METs = kcals burnt per hour
A slow run, where you can hold a conversation, would be approximately eight METs per hour. So a runner weighing 75kg would burn 600kcal per hour (75kg x 8METs). And if you ran for 20 minutes this would be the equivalent of 200kcal.
Meanwhile higher intensity running, where you are unable to speak continuously, has a MET rate up to 16. Weight training in the gym is around six METs, HIIT workouts range from seven to 12 METs and cycling at a low intensity would be approximately four METs, increasing to 12 METs at higher intensities.
You can estimate the MET of different activities using this calculator.
'This is a rough estimate and there are lots of things that will impact it like your muscle mass, age and whether you are biologically male or female but it gives people a starting point to use,' explains Rogerson.
Should I be keeping track of the calories I'm consuming?
The recommended daily calorie intake for the average male is 2,500kcal, while for women it's 2,000kcal, although this will vary from person to person, depending on factors such as age, height, weight and genetics.
If we eat more calories than we burn, our bodies store the excess as body fat and this can cause us to put on weight over time.
Knowing the calorie content of food and drink and how much we are consuming per day can therefore make it easier to keep track of our intake. This can be done via weight loss apps, keeping a food diary, or checking the labels on shop-bought foods.
This can, however, be tricky and time-consuming and is not always necessary – you can take steps to ensure you are not consuming excess calories, such as adjusting portion sizes and making sure your meals are made up of the right types of food (more on that below).
How to develop a weight loss exercise regime
Losing weight in a gradual, sustainable way is the healthiest approach to take. 'In terms of safety, a small energy deficit for most people is probably going to be better than something that's quite drastic, particularly if they're exercising,' says Rogerson.
If you do not exercise at all and eat a high calorie diet then even a small change could make a significant difference. A calorie deficit of around 500 calories per day achieved through a combination of diet and exercise is a sustainable target. This would equate to one pound of weight per week. But remember that weight loss is not linear in the short term, so how much you weigh will fluctuate week to week.
'One session of exercise a week is a good starting point for someone who does no exercise at all. And then over time you can add another session and get to the point of three sessions a week,' recommends Rogerson. 'At this point you can add to the duration and intensity of the sessions. The Couch to 5K programme is a great because it starts off small and gradually progresses week to week.'
Another approach to weight loss it to conduct it in stages. For example, if you want to lose 10lbs, the first 5lbs could be lost over five weeks, and then you could take a short break to maintain your weight – consuming the recommended daily calorie intake of 2500kcal for men and 2,000kcal for women – before the second five-week block to lose the remaining 5lbs.
It's important to remember that the higher your body weight, the more energy you will expend during exercise. This means you will probably see greater weight loss at the beginning of a training programme, but as you become lighter your metabolism will slow down because metabolism is linked to body size. Over time your body will also become more efficient at exercise so it is completely normal for weight loss progression to slow down.
'To continue weight loss we need to either progress the exercise to make it more challenging to maintain the same amount of energy expenditure or to reduce calories over time, otherwise plateaus will happen,' explains Rogerson.
The dangers of using exercise to lose weight
Burning too much energy, too quickly, can lead to low energy availability which means our bodies do not have enough energy for normal physiological function. This can create long-term health problems and potentially hamper future weight loss, as the reward chemistry in the brain is altered, meaning we crave fat and sugar.
Doing too much exercise too soon can also increase the risk of injury, particularly through impact exercise like running, and lead to fatigue and burnout. It is also more difficult to sustain and may develop into a long-term lifestyle change that could lead to exercise addiction and disordered eating.
Dramatic and sudden weight loss can also cause Relative Energy Deficiency in Sport (RED-S), which affects hormone levels. This can lead to a drop in testosterone in men and impact thyroid hormone levels, while for women insufficient calorie intake can cause hypothalamic amenorrhea, or the absence of menstruation. The long-term consequences of RED-S include decreased bone density, cardiovascular issues, gastrointestinal disturbances and decreased immunity.
If you think you might be experiencing RED-S or you think your relationship with food and and/or exercise has become unhealthy, you should stop any weight loss programme immediately and seek help from a mental health professional. If you are struggling in any way, you can find information and support on Beat's website.
How to incorporate a healthy diet
Eating a balanced diet which is high in fibre and protein and lower in sugar and fats is the best approach, rather than cutting out entire food groups.
This includes lots of vegetables, high fibre starch-based carbohydrates like wholegrain breads, pasta cereals and brown rice and protein which has a satiety effect making us feel fuller for longer.
Try to avoid ultra-processed foods, which is food you cannot recreate in your own kitchen, such as reconstituted meats, fruit yoghurts, vegan substitutes and confectionary. But equally, it is also important to be flexible and not take a diet on, diet off approach, says Rogerson.
'If you go out for a meal with family and have a dessert then some people think they have blown the diet so the whole weekend is lost and they can eat whatever they want and start again on Monday. This is associated with poor weight loss. A more positive approach is to think, OK, I've enjoyed a lovely dessert and now I'll go back to healthy eating as I normally would,' he adds.
It is also important to make long-term lifestyle changes to maintain a healthy weight once you have reached your target. 'If you revert back to what you were eating before, you are not going to sustain weight loss. One of the reasons people end up regaining weight is because the decisions they're making about weight loss don't reflect the foods that they like to eat. So we need to think of it in terms of: what do I need to do for the rest of my life to sustain this?' says Rogerson.
What do you need to start exercising?
It is important to see a health professional such as your GP, before embarking on a new exercise and weight loss programme.
It is also a good idea to make sure you have clothing that fits properly to avoid chafing, that is lightweight and made from a quick-drying material. It is also worth getting some proper footwear fitted in person.
You don't need to spend a lot of money: all you need is a pair of shorts, a t-shirt, sports bra for women and a pair of trainers.
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