14/05/2014 09:55 BST | Updated 22/05/2015 06:12 BST

How To Beat The Middle Age Spread

How to beat the middle age spreadRex

You swear you're not eating any more but somehow you are a stone heavier than you were last year. Weight gain happens slowly and it's not until we realise our favourite item of clothing is feeling a bit snug that we stop and take stock.

It is a frustrating fact of life that our metabolism slows as we get older (two to four percent each decade over the age of 40), which means that without necessarily eating more than usual, we find ourselves with a gradually expanding midriff – the dreaded 'middle aged spread'.

But the good news is that it's not inevitable – it is about understanding your body's changing energy requirements. Once you know this, you have the key to weight loss success.

The problem is that the balance between maintaining weight and gaining weight comes down to a very small difference in calories. If you eat just two chocolate biscuits a day more than your body needs to meet its energy requirements, you will gain 1 stone 7lbs in just 12 months!

However the good news is that if you turn that around and cut out just a couple of small treats a day, you could lose the same amount of weight over the same time period – and it probably wouldn't even feel like you were trying!

The key to boosting metabolism

Of course food is only half of the equation when it comes to weight gain – we all know we should be exercising more too. But this isn't just about burning extra calories (although that obviously helps to keep our weight in check), another vital benefit is that it helps to prevent muscle loss that happens with age.

Losing muscle has a negative effect on metabolic rate. Muscle is a metabolically active tissue requiring energy, so it burns calories just by being there. Regular exercise is essential to maintain muscle – the more we have, the higher our metabolic rate will be. (Plus it's essential for good posture – it's true that pulling in your 'core' muscles can make you look instantly slimmer!) Less muscle, unfortunately also means more fat, but fat doesn't burn energy so this change in balance between muscle and fat will mean that you have less 'chance' to burn calories.

As you get older, making sure your gym workout focuses more on strength training to maintain muscle mass and tone is really important.

Combating the weight gain

The principle is simple – burn more calories than you consume, and you WILL lose weight! However what you need to do is to measure this accurately and get the calorie deficit right for weight loss.

A very good starting point is to keep a food diary. This approach is recommended by doctors and dietitians as health professionals know that the simple act of focusing a person's attention on what they are eating and drinking is a powerful way to change behaviour.

Research into this method found that keeping a food diary while dieting can double weight loss (Kaiser Permanente Centre for Health Research). A more recent study published in the Journal of the Academy of Nutrition and Dietetics looked at dieting methods among 123 women and concluded that the best piece of advice was to 'keep a food journal to help meet daily calorie goals'.

The food diary approach does not provide a diet plan to follow – it's more about re-educating your eating habits by helping you to start by modifying what you currently eat. If a diet is something you are going to be able to stick with for longer than a few weeks, it has to be down to you to decide and control what you eat.

The aim is knowledge is power! Using a food diary gives you the information to eat smarter and make healthier food choices. The more food diary entries you make staying within your calorie allowance, the more weight you will lose.