Everything you think you know about calories is BUNKUM

Stop fretting about the Christmas blow- out because TV obesity expert Dr Giles Yeo reveals in a new book...

NO ONE wants to hear the word ‘calorie’ at Christmas. Yet the preamble to the big day – during which most of us stuff ourselves silly – is always dogged by guilt, worry and predictions of the pounds we will inevitably pile on.

Then January hits, along with our commitment to the ‘new year, new me’ philosophy, and we find By Dr Giles Yeo ourselves obsessively counting calories – until February anyway.

Calories are said to tell us everything there is to know about food; healthy or unhealthy, fattening or slimming. Even the Government seems to think so, with plans announced to introduce mandatory calorie counts on restaurant menus in an effort to tackle obesity.

But for us scientists, this obsession with calories is increasingly difficult to swallow.

There’s no question that if you are morbidly obese – or even just carrying a few extra pounds that increase your risk of serious illnesses such as type 2 diabetes – then counting calories is crucial.

Mounting evidence suggests that drastically reducing calorie intake can even REVERSE diabetes, without t he need for medicine. So low-calorie diets do have an important role to play.

But for the majority of us, religiously recording our calorie intake for a few days over the Christmas holidays is largely pointless. Why? Because what your packet of pigs in blankets says is the calorie content and

the amount you absorb when you eat them can be radically different.

The discrepancy is down to a vital concept called caloric availability: how many calories the body will absorb when you eat a particular food. It’s fundamental to keeping our weight under control, yet barely anyone has heard of it. It means that pack of festive mixed nuts may read 180 calories but your body may only absorb 120.

On the other hand, that delicious turkey crown, when raw, will probably pack about 160 calories for every 100g of meat, but once it’s cooked this could be almost 50 per cent higher – thanks to additional calories made available after cooking.

This Christmas, I want you to stop believing everything you read on food labels and arm yourself with the real secrets to calculating calorie content. Once you have done that, tuck in!

WHY THOSE NUMBERS ON FOOD PACKAGING ARE OFTEN WRONG

SEVERAL recent studies have found manufacturers’ calorie measurements could underestimate or overestimate levels by as much as a third.

Typically, food companies measure calories – a unit of energy – using a machine called a bomb calorimeter.

This involves burning food to a crisp in a sealed container, surrounded by water. As the food is burnt, the temperature of the water increases. It is this increase in temperature that determines the amount of calories in food.

In other words, a calorie is the amount of energy it takes to increase the temperature of a kilogram of water by one degree centigrade. As we all know, adult men need about 2,500 calories a day to keep the body working efficiently, and women about 2,000.

Extra calories from carbohydrates are first stored as glycogen – strings of sugar – in the liver, muscles and brain. But once those stores are full, everything else including spare fat and protein is stored as fat. This is why, if you consistently eat too many calories, body fat increases.

But the bomb calorimeter relies on every morsel of food we eat being burned to a crisp inside nside our bodies. Some remnants of food ( and d the calories they contain) inevitably escape absorpsorption and digestion, and different foods are easier asier or more difficult to digest.

HOW COOKING YOUR SPROUTS MAKES THE CALORIES SOAR

SURPRISINGLY, cooking vegetables like sprouts, cabbage, broccoli or cauliflower can significantly increase the calories you absorb. That’s because plants contain a compound called cellulose. It helps cells hold d their structure but is rich in calories.

Digestive enzymes in the stomach can’t break eak cellulose down when we eat vegetables raw. w. But cooking releases more of it, giving greater access ccess to the energy inside the plant cells.

The longer veg is cooked, the more cellulose i s broken down and the more calories we absorb.

Celery is another example. A stick is said to have a meagre six calories, but put it in a stew or soup and you’ll increase this number five-fold to 30, simply by breaking down the cellulose.

Some studies show that slowcooked lentil soups, pureed pulses such as houmous and refried beans are up to 30 per cent higher in available calories than the ‘al dente’ equivalent.

These studies measured calories in faeces after the person ate an ingredient, and then subtracted the number from the figure listed on the back of the packet.

This gave researchers a more accurate measure of how many calories the body actually absorbs from a particular food.

ROASTING THE TURKEY HAS THE SAME EFFECT

COOKING methods for meat, including the Christmas turkey, have a similar effect – unlocking secret calories. While some supermarkets may record content in the meat’s raw state, cooking – depending on the method – can boost the amount you absorb by almost 50 per cent.

This is because cooking meat fully, or for long periods, releases extra calories that are tied up in muscle fibres we would not be able to access if we ate the meat raw. On the other hand, having your juicy rump steak ‘rare’ rather than minced up for a meat sauce could save you almost a quarter of the 270 calories quoted on the label. A major 2011 study highlighted this effect by feeding two groups of mice meat and sweet potatoes prepared in four ways – raw and whole, raw and pounded, cooked and whole, and cooked and pounded – for 40 days.

Scientists found that mice that ate raw and whole food absorbed significantly fewer calories than those in the cooked and pounded group.

The cooked and pounded group were also found to have gained the most weight.

YOU BURN ENERGY EATING A DRUMSTICK – HONESTLY!

CALORIE-watching shouldn’t just be about what you consume when eating but also how many calories you burn in the process. And while it hardly counts as physical exercise, believe it or not, you burn precious calories when you tuck into a juicy turkey drumstick.

When Harvard University scientists studied 260 overweight adults they found high-protein diets – with lots of meat – helped them shed significant amounts of weight.

There are two reasons for this. Firstly, protein takes longer to digest than carbs, so makes you feel fuller and therefore eat less. But most interestingly, those on the high-protein diets burned an average of 250 more calories each day over a course of 20 weeks.

This is because digesting protein, such as meat, is tiresome and complex as it involves breaking down protein into its building blocks, called amino acids – essential for cell renewal, growth and muscle repair. It is so painstaking for our bodies that regardless of how protein is cooked, roughly a third of t he calories consumed are required to digest it.

Carbohydrates, on the other hand, require only about five per cent of the calories they provide to digest them. But don’t ditch carbs just yet; some studies looking at populations who eat high-protein diets show them to have an increased risk of cancer.

Researchers from the University of Southern California suggest one reason could be due to increased levels of a compound called IGF-1, which promotes tumour growth.

Sugar, meanwhile, requires the

least effort as it is made up of molecules small enough to pass through our cells quickly. This means the energy it provides is released very quickly into your blood in a burst.

Digesting fat is a longer process – so may sustain fullness – but only burns about three calories for every 100 eaten.

A CHEESEBOARD COULD BE GOOD FOR YOUR WAIST

IT MAY sound like an unlikely slimming aid, but the Christmas Day cheeseboard could hold the secret to burning more festive calories. Studies show that cooking carbohydrates, like pasta and rice, with additional fat (such as grated cheese) makes us feel fuller for longer by slowing down digestion and providing a controlled release of sugar in the blood.

Fat is more chemically complicated than carbohydrates, so it’s harder and more time-consuming for the body to break down. Adding fibre has a similar effect. A fascinating study by researchers at Claremont University in California found people who ate 600- or 800calorie portions of fibre-heavy wholewheat bread (with nuts and seeds on it) burned twice as many calories digesting the food as those consuming the same calories eating white bread.

What’s more, t hey absorbed ten per cent fewer calories – even though their intake was the same.

Fibre also slows digestion. But recently scientists have discovered there may be another reason for its benefits.

The stomach contains 100 trillion or so healthy bacteria, called the microbiome, which not only release hormones to promote feelings of fullness but also feed on fibre, using up energy in the process.

Researchers from the University of Iowa found that mice with wellfed gut bacteria burned significantly more calories and weighed ten per cent less than animals with depleted microbiome.

In other words… fibre’s painstaking journey from your mouth to the bowel makes us eat less, and burns a fair amount of calories.

DON’T POSTPONE YOUR FEAST TO THE EVENING

THOSE who choose to eat their turkey and trimmings at dinner time – or past 7pm – could end up consuming more calories.

From an evolutionary perspective, humans have always used energy most efficiently in the daytime, burning more calories.

During daylight, prehistoric people needed optimum activity of their bodies to hunt food, avoid being eaten and reproduce. This still helps set our circadian rhythm – the body’s internal clock that helps us distinguish between daytime and night.

While we’re no longer chasing wild animals with a spear, our metabolism remains most active in the daytime. As the brain and body begin to wind down, temperature drops – usually at about 7pm – and hormones send signals to the digestive system indicating that the calories from the food we eat are not immediately required.

This means they are more likely to be both absorbed and stored as fat.

Studies by researchers from the University of Murcia in Spain found that dieters who ate lunch after 3pm every day for five months lost three pounds less than those who ate lunch at 2pm or earlier – despite eating exactly the same number of daily calories.

And nocturnal mice that eat during the daytime see their body fat percentage increased by seven per cent, compared to those fed the same number of calories during the night when they are awake, according to recent US studies.

TUCK IN… IT’S THE ONE DAY YOU SHOULD

DON’T get me wrong – listing calorie content isn’t completely pointless. Some studies suggest t hat reading t his i nformation can trim calorie intake by about eight per cent.

But telling consumers the number of calories provided by each food group, categorised by cooking method, would give a more accurate representation of what is happening inside our bodies.

Realistically, I can’t see that happening any time soon.

For now, take all calorie listings with a big pinch of salt. Except on Christmas Day, when I would strongly encourage you to ignore them altogether…