This is the one fatal mistake so many dieters make trying to lose weight

It's so easy to fall into this trap when you're trying to lose weight and shed body fat.

People think the first thing they need to do to lose weight is just cut out every food they think is 'bad' and reduce their calorie intake to Draconian-low levels. But just as overeating can be bad, you have got to be careful of under-eating too. If you're following a specific diet or eating plan and doing regular exercise at the same time, then you need to make sure you're eating enough to keep your energy levels high and sustain your training regime. If your calorie intake is low and you're burning what little do you eat off in the gym, then you run the risk of under-eating. Lead dietician at the Dallas Eating Recovery Centre, Kathryn Johnson, explains how detrimental under-eating can be:

"Under-eating ultimately leads to more weight gain and another extreme diet," she says.

The reason is basically your metabolism. Your body doesn't like losing weight. It likes to be just how it is with lots of stored fat, so if shit goes down then you can survive the winter. So when you start cutting calories out, it quickly realises and slows down your metabolism accordingly so you're burning through less energy through the day. This is bad for weight loss because if you're trying to burn fat then you want a metabolism that is on fire and burning through calories like a furnace. So when weight loss slows down or plateaus, people immediately cut more calories and so this process continues - metabolism slows, weight loss slows. And so on... This is until calories become so low, something has to give. That's normally you ending up giving into your body's cravings for calories and binge eating. People get stuck in this cycle or starvation and then bingeing but it can make weight gain creep up on you while your hormone levels will be on the floor. How do you make sure you don't fall into the under-eating trap then? You might be sick of hearing it, but a balanced diet is key. Johnson says you need to be "calculated" about how many calories your body needs to keep going, keep your metabolism high and keep the weight coming off. Figuring out this number is dependent on a number of factors including age, how often you exercise, metabolism and your daily physical activity which is often largely dictated by your job and your training levels. You can work out this number quite easily with this simple calculator. It works out the basic amount of calories you need to survive and then the total calories you need in a day when all your exercise and activity is included (this explains in depth how it all works). It gives you a much more accurate picture of what you should be eating to lose weight effectively and healthily. Johnson also recommends looking at what you eat in a day and making sure that all food groups are catered for:

"When looking at your daily intake, you should be including foods from all five food groups—fruits, vegetables, grains, protein, and dairy—in order to get the nutrients you need. Make sure you're varying your menu for a more balanced approach to weight loss."

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