Exercise for weight loss: how much is enough?

There's an age-old debate – does exercise help boost weight loss or not? It's widely accepted that following a calorie-restricted diet is the biggest factor when trying to lose weight – but perhaps less generally so that exercise can have a significant role too.

As with many things, it's very much a grey area. Not least because the term 'exercise' is very general. Does this mean a short walk? A daily run? One weightlifting session a week? A couple of HIIT sessions a week? The fact is, this matters a lot – when it comes to exercise and weight loss, frequency, type and duration are all important.

Here I'll discuss what role exercise can play in weight loss and what the recommended frequency of exercise is for boosting weight loss success.

But before I get into the whys and wherefores, here are a few things to consider:

1. You can't out-train a bad diet.
2. You can't out-train a bad diet.
3. You. Can't. Out-train. A. Bad. Diet.

Okay, I know I've repeated that three times – but it's such an important point. If you hit the gym three times a week but pay no attention to your diet, it's unlikely you're going to significantly impact your weight. This is because it's incredibly challenging to cancel out large amounts of overeating with exercise – unless you're logging major calorie burns. So first things first, an appropriate diet must be followed. Regular exercise can then help to boost weight loss and help keep you on track.

Another reason to focus on your diet is that there's a tendency to subconsciously eat more to compensate for exercising, if we're not mindful of this. One study found that participants who burned off 1,500 or 3,000 calories per week through exercise, all ate an average of 1,000 calories per week more [1]. So it's common to see people eat more when they move more, but, interestingly, both groups capped at around 1,000 calories extra, suggesting the more exercise we do, the less impact our compensatory eating may have.

With that said, if we are following an appropriate weight loss diet, as well as including regular exercise – how often do we need to exercise to have a significant impact? Let's discuss.

Exercise frequency

How often we should exercise to help boost weight loss largely depends on the duration, intensity and type of exercise being completed. Suppose, for example, you ran a marathon once a week. In that case, chances are you'd be burning over 2,000 calories on that long run alone – enough to impact your calorie deficit significantly. But, for most of us, this isn't the case, or achievable. Typically 3-4 hour exercise sessions per week is much more realistic for most people. But is this still enough and if so, how long should each session be to boost weight loss?

One study allocated participants to either a high-frequency (HF) or low-frequency (LF) exercise group for a 24 week study [2]. Both groups completed 300 minutes of exercise per week, but the HF group did 50 minutes, 6 times a week, and the LF group did 100 minutes, 3 times a week. The results found that both groups lost weight, but the low-frequency group lost slightly more weight. This suggests fewer sessions of a longer duration could be more impactful on weight loss. It's worth noting that both groups were also on a weight loss diet – but the difference in weight loss between the groups highlights the impact exercise can also have on progress.

Another study looking at exercise frequency and weight loss found a significant difference in weight with the group that completed 30 minutes of exercise 4 times a week – compared to those exercising 2-3 times or less than 2 times [3]. So these findings suggest that a higher frequency is needed to have an impact. However, the duration of each exercise session was much less than in the previous study, implying that the number of exercise sessions each week is less important than the total number of exercise minutes completed each week.

The World Health Organisation (WHO) recommends we complete 150 minutes of moderate intensity exercise each week for good health. Some research suggests we should double this amount when aiming to lose weight [4]. This would mean completing 300 minutes of exercise per week, which is consistent with the high-frequency and low-frequency exercise study mentioned earlier. So as general guidance, if weight loss is your goal, aim to complete around 300 minutes of moderate intensity exercise each week, which could look like any of the following:

• 3 x 100 minute sessions
• 4 x 75 minute sessions
• 5 x 60 minute sessions

Exercise type

That said, the type of exercise in terms of intensity is important. If you are doing high-intensity workouts – less duration is necessary. But lower-intensity workouts would require a longer duration. So it may well be that 200 minutes of activity per week is adequate if you're doing 60 minutes of high-intensity exercise and 140 minutes of moderate-intensity exercise for example. In fact, WHO recommends 75 minutes of intense exercise each week or 150 minutes moderate – so a smaller duration is necessary with high-intensity workouts.

In terms of the best type of exercise for weight loss, research does suggest that aerobic exercise alone or a combination of aerobic and resistance training can help to boost weight loss, when used alongside an appropriate calorie controlled diet [5]. Resistance training alone, while it does promote big changes to body composition, is unlikely to significantly impact weight without the addition of aerobic activities too which are good calorie burners [5]. General recommendations are to complete a variety of activities from resistance training, to aerobic and HIIT to avoid getting bored and promote the best improvements in fitness and body composition, as well as boost weight loss success.

How else does exercise help?

If exercise is carried out often enough and for long enough, the research does suggest it can help to improve weight loss results. This is directly related to the calorie burning potential of exercise. But it can also play a huge role in a less direct way. When we exercise, it makes us feel good – in fact exercise is proven to boost our mood [6]. This can have a big impact on our motivation to stay on track with a weight loss plan and to keep showing up. Being active regularly helps us take some control of our health and lifestyle, which can go a long way to nurturing a healthy mindset. This can encourage better food choices ongoing.

Final word

To summarise, our diet is hugely important when it comes to losing weight, but exercise does have a role. The research suggests aiming for 300 minutes a week of moderate intensity exercise could have a significant impact on weight loss success – which for most of us looks like at least 4 sessions a week, lasting a little over an hour. It's also important to note that exercise can do so much more than burn calories – it improves health, boosts mood and helps promote a positive mindset. So remember – while you can't necessarily run away from a bad diet, you can run towards a healthier lifestyle!