Why is it easier to create a calorie deficit by tracking and reducing your calorie intake as opposed to increase your calorie burn?

In theory you can create a calorie deficit in both ways, you can eat less or move more (or meet in the middle and do a bit of both). Generally though, I’d tend to push people to focus on calorie intake over what your burn and here’s why.

It’s pretty hard to track how many calories you have burnt a day. You can get idea of your TDEE across the week based on your general activity levels, but how many calories your burnt in that specific HIIT class or on that run is difficult to put a number on (smart watches calorie burn figures are normally massively inaccurate). Beyond that you need to remember that your TDEE will take into account your normal activity levels, so those calories have already been accounted for, so at what point do you know you’ve done ‘extra exercise? The answer is in reality you don’t. So how much you expend is a rough figure, but you can track how much you consume with much more accuracy. Of course it’s never going o be spot on to the nearest calorie but with apps like My Fitness Pal you can track your intake for free and to a reasonably accurate level. The fact that trying to monitor what you eat allows you more accurate data to sue means you’re more likely to be successful sticking to a calorie deficit if you try to adjust what you eat instead of trying to increase what you burn. If on top of this you then also look to move more (which I’d full encourage) you will find you can increase your calorie deficit a bit more and maybe assist your results.

The other aspect of creating a calorie deficit by burning more calories instead of eating less comes if you are already quite active. If you currently do nothing and then start walking daily and maybe doing planned exercise once a week, then you will probably find that you can eat the same and lose weight. You might also find though that you’re more hungry because you’re doing more so you end up eating more too. Without tracking this is a very hit and miss approach.  Now if you are already quite active and want to create a deficit through exercise the issue comes from how much more can you do in reality?  Unless you want to spend all your time in the gym how realistic is this going to be for you?  

The one time I’d be mindful of making a deficit a mixture of reducing intake and increasing output is when someone is quite small and already quite light. This is going to give them a smaller TDDE to start with and so creating a calorie deficit by food alone might leave them with a very small daily calorie amount. In cases like this a missed approach could be beneficial, however equally, it might be that a review of goals and a decision of whether weight loss if the best goal here or whether body recomposition might be a better focus.

Ultimately there are multiple ways you can create a calorie deficit. Using one which allows you to track accurately will allow you to assess progress and when you start to plateau or are noting getting results as you think you should be you have real data to use to assess why and what you can do to change that.