Experts In Focus - Laura Tilt

Posted 15 May 2009

Hi there I’ve been following the Fitbug challenge and I've lost only one pound. I've done everything - kept a food diary, exercised more etc. The diary has shown me that I always over-do the carbs and under-do the fats in my diet, despite my average intake being around 1,000 calories. I know I need to cut down the carbs (most of which come from my small bowl of muesli I like at the beginning of the day) but not sure what to substitute them with without upping the fat and therefore calories. Any tips?

Thanks for your question. Firstly, you definitely shouldn’t be disappointed with your weight loss - losing 1lb a week is actually great progress! Losing weight at a rate of 1-2lb a week (0.5-1kg) is recommend because it is healthy and sustainable. Losing weight faster than this can be dangerous and may actually reduce your ability to lose weight in the long term - I’ll explain why later.

A pound of fat is equivalent to 3,500 calories, so, in order to lose a pound a week, you’d need to use 500 calories more than you take in each day. The best way to do this is through a combination of diet and exercise, so for example, reduce your food intake by 250 calories and burn an extra 250 calories through exercise. Whilst this sounds like a lot of calculations, you don’t need to worry about working this out as Fitbug does it all for you - if you stick to the calorie recommendation and achieve your steps targets you should lose 1-2lbs a week.

However, in your question you mention that your average calorie intake has been around 1,000 calories which is actually far too low. Eating too few calories is a common mistake people make when trying to lose weight because the assumption is that the fewer you eat, the quicker you will lose weight - but unfortunately this is not the case!

If you eat too few calories, your body assumes a food shortage and adopts a starvation mode where by it starts working more efficiently (i.e. uses fewer calories) in an attempt to protect fat stores and energy. This happens with any diet, but is increasingly pronounced the lower your calorie intake.

The net effect of this is that you burn less calories, which means any weight loss will sooner or later slow to a stop - with your metabolism now running at a lower rate you would need to eat even less to lose weight, which lowers your metabolism further, and you enter a viscous cycle. What’s more, when you start to eat 'normally' again, you’ll regain weight quickly as your metabolic rate remains depressed, at least for a period post dieting.

The other downside of very low calorie diets (apart from feeling very hungry and lacking in energy!) is that they cause a greater loss of lean tissue, i.e. your body will actually burn muscle preferentially to fat. This isn’t a good idea as muscle is metabolically active and losing muscle can further reduce your metabolic rate.

Whilst this all sounds a bit depressing (!) there is plenty you can do to prevent these effects. First off, Fitbug never advocates eating fewer than 1,400 calories due to the detrimental effect on body composition and metabolic rate. If you check your nutrition pages you should find your personal calorie recommendation - this is based on a number of things including: your current weight, age, gender and level of physical activity. This has all been calculated to help you lose weight at a safe rate so my first piece of advice is to stick with this.

Secondly, activity helps to offset any metabolic reductions caused by dieting - which is where your steps targets come in. Exercise helps to boost metabolism and also protects muscle mass. If you can, add some resistance exercise to support your muscle tone.

Now regarding your carbohydrate intake, carbohydrates are the body’s preferred source of energy and should form around 50% of our diet. However, if you’re cutting down on fat in order to lose weight, you’ll find that your carbohydrate intake will increase to reflect the deficit of fat - and this is fine, just remember to choose wholegrain carbohydrates where possible (e.g. wholemeal bread, brown rice) as these contain fibre, are digested more slowly and therefore keep you fuller for longer. Combining a carbohydrate and protein food at each meal will help to keep your energy levels steady throughout the day.

Finally, remember that a slow weight loss is the best kind and will stay off! Losing more than 2lb a week is a sign that your body is losing muscle as well as fat and this will be detrimental in the long term as the weight is unlikely to stay off.