The claim

It’s calories that count when it comes to weight loss, not uniquely calories from sugar.”
American Beverage Association statement

The background

Sugar is becoming the big dietary villain of our times.

We used to think it was saturated fat that made us fat. But fat consumption fell and we carried on getting more obese and unwell.

All those low-fat products on the supermarket shelves just happen to be full of added sugar.

A swelling chorus of doctors and dieticians are now warning that the white stuff is the real culprit, leading to higher rates of diabetes and other illness as well as expanding waistlines.

Last week the World Health Organization (WHO) recommended people halve their sugar intake.

Is this just another fad that will be replaced by another dietary bogeyman, or is it really time to yank out our sweet tooth?

The analysis

The food industry is at war with a very vocal group of campaigners on the issue of whether we should restrict or tax sugary foods.

The big question is whether it’s fair to pick on sugar. Are we eating too much generally, taking in too many calories from fat or starch or sugar or whatever, or there is something particularly bad about sugar?

Big Food’s position on this could not be clearer.

The industry-funded World Sugar Research Organisation (WRSO) says: “Over-consumption of food energy, whatever its macronutrient composition, and inadequate physical activity may lead to body weight gain and increase risk of Type 2 DM (diabetes mellitus).”

Coca-Cola says: “All calories count, no matter where they come from.”

The American Beverage Association: “It’s calories that count when it comes to weight loss, not uniquely calories from sugar.”

Get the idea?

Anti-sugar campaigners are equally adamant that there is something especially bad about sugar and we need to single it out for attention.

General advice about getting less calories overall and more exercise just won’t cut it.

There is surprisingly little medical research that gets to the crux of this question.

In order to isolate the effect of sugar we need to get two groups of people to eat the same amount of total calories, but vary the amount of sugar within the diets, then track the results.

Large-scale, long-term studies of this kind are few and far between.

Before it issued its recent draft guidance on sugar, the WHO commissioned this review of the evidence on sugar intake and body weight, published in the British Medical Journal last year.

The conclusions are actually very cautious, with the authors finding “rapid weight gain that occurs after an increased intake of sugars” but concluding that “the extent to which population-based advice to reduce sugars might reduce risk of obesity cannot be extrapolated from the present findings”.

The team found 12 studies which kept total calories the same but varied sugar intake, swapping sugar for more complex carbohydrates like bread and potatoes in one group.

They “saw no evidence of difference in weight change as a result of differences in sugars intakes when energy intakes were equivalent”.

The researchers added: “The data suggest that the change in body fatness that occurs with modifying intake of sugars results from an alteration in energy balance rather than a physiological or metabolic consequence of (simple sugars).”

It’s possible to see this as a victory for the food industry – a validation of what they have been saying all along.

But this isn’t the end of the story.

These studies limited participants to a predetermined number of calories a day, something not representative of reality outside the laboratory.

What if eating a lot of sugar makes it harder for you to limit your overall calorie intake in real life?

Some doctors have suggested that sugary soft drinks are associated with weight gain because of their “low satiety”.

In other words, you don’t feel full after guzzling a can of cola, even though you’ve taken hundreds of calories on board, and you eat just as much later.

Others say sugar may be physically addictive, acting on the brain in the same way drugs like cocaine do, but most positive evidence comes from experiments on lab rats, not humans.

Dr Robert Lustig, an American paediatrician at the forefront of the campaign against sugar, says the body reacts differently to sugar than other foods.

His theory is that sugar causes a unique spike in the hormone insulin, which tells the body to store fat and blocks another hormone that tells us when we are full.

When he gives obese children a drug to reduce the insulin response, they start eating less and losing weight.

The theory has some supporters among doctors but remains controversial.

So far we have been talking about weight gain and obesity, but new research suggests sugar carries other dangers besides an expanding waistline.

Last year a US study using long-term data from 175 countries found an association between the availability of sugar in a population’s food supply and rates of type 2 diabetes.

The trend was independent of obesity rates and a host of other possible confounding factors.

Increasing sugar by 150 calories per person per day was correlated with a 1 per cent increase in the prevalence of diabetes in a country’s population.

An extra 150 calories of any other type increased the diabetes rate by just 0.1 per cent.

Another US study published last month found a significant relationship between eating more added sugar and the risk of dying from heart disease.

Again, this was independent of body mass and index physical activity.

The verdict

The sugar industry maintains that excess calories are the problem, not excess sugar.

Purely on the issue of weight gain, it’s interesting to note that the very researchers commissioned by the WHO before it updated its sugar guidelines actually tentatively back the industry on this point.

That doesn’t mean sugar is off the hook. It means more evidence is needed to settle the point one way or the other.

New research linking sugar with diabetes and heart disease is interesting and the industry has not come up with an answer to it yet.

The WHO has added its voice to the growing number of doctors who have decided that there is enough evidence of various health risks to start advising people to cut down on sugar now.