Does Sugar Make us Fat?

If you get your nutrition advice from a woman’s magazine, you will probably be under the assumption that sugar is the source of all evil. Fear not, my fellow sweet tooth; you can indeed have your cake and eat it – and enjoy it! This current attack on sugar is ludicrous, and just another scapegoat for the obesity ‘epidemic’. Through reading the next few paragraphs, you too will be more informed to make flexible choices in your diet, leading to more long term success and better weight management without having to deprive yourself.

So where does this idea that sugar makes us fat come from? Well, there are a load of theories which look at how insulin raises when we eat foods high in sugar. Insulin is a hormone which helps shuttle carbohydrates into fat stores, and also works to inhibit fat burning. High insulin levels are also linked to obesity. All this makes it seem, to the uneducated observer, that sugar causes fat. But is there any substantiation to this claim beyond wild accusations from petri dish observers viewing a small time scale out of context to the human body in the grand scheme of things? In short – no.

Surwit and colleagues (1997) compared two separate diets, one containing 43% table sugar and one with just 4% table sugar. These people completed 6 weeks of these diets, and then the results of their body composition were taken. The results? There were NO SIGNIFICANT DIFFERENCES seen in both the loss of bodyfat or bodyweight between the two diets. So a diet almost half in sugar produced the same weight loss as one devoid of sugar. On top of this, a whole load of biomarkers and things such as satiety remained the same for both groups.

But I thought sugar enters your blood faster and raises insulin more

It does – but weight gain/ loss is more complicated than simply blaming one hormone and the amounts/speeds that it raises. You can look at short term studies all you want, but the real answer is in the long term trials.

In 2008 Aston et al. studied the effects of glycemic index on bodyweight in overweight and obese women, finding no correlation between faster acting carbohydrates and increases in weights when calories are the same. So even when the carbohydrates come into your blood at a faster/slow rate or insulin released is high or low it doesn’t mean you will get fat.

What does this mean for me?

What it means is that, in terms of weight loss, eating sugar is not going to impede your goals. In fact, if you are a sweet tooth like me, eating sugar can help you achieve your weight loss goals. Depriving yourself of some sweet things will more likely damage your motivation, leading to ditching the diet and stalling your weight loss/gaining weight.

Weight loss is a product of being in a calorie deficit, regardless of what your diet looks like. Look at This Study by Sacks Et al (2009) comparing diets with different amounts of carbs, protein and fats. There was no difference in the weight loss or lipid profiles of the subjects, even though they ate wildly varying diet compositions. Sure, I would make sure your protein intake is adequate (1 gram per pound of bodyweight) to ensure you lose more fat than muscle, but after that, feel free to make flexible choices with your calories.

Take home message

As usual, when it comes to weight loss, calories are king; set your weekly goals for calories and stick to them. Don’t deprive yourself of a bit of sugar every now and again, if you want a bit of cake and it fits into your calorie allowance, go ahead and enjoy it.

I should point out that I am not advocating a diet full in sugar. Whilst this could (as demonstrated by the scientific study) produce weight loss, it would not provide you with adequate nutrition in terms of vitamin, mineral, fibre, content etc. I would limit sugar intake to 100 grams per day if you are sedentary, and allow more if you are active. Don’t go crazy and eat nothing but sugar, but at the same time don’t completely eliminate it from your diet in the fear that it will make you fat (it won’t).   

As always, eat food high in nutrition on the whole, but enjoy sweets in moderation.

Scientific References

   Surwit RS, et al. Metabolic and behavioral effects of a high-sucrose diet during weight loss. Am J Clin Nutr. 1997 Apr;65(4):908-15.

Sacks FM, et al. Comparison of Weight-loss diets with different compositions of fat, protein and carbohydrates. N Engl J Med. 2009 Feb 26;360(9):859-73.  

Aston LM, Stokes CS, Jebb SA(2007). No effect of a diet with a reduced glycaemic index on satiety, energy intake and body weight in overweight and obese women. Int J Obes (Lond). 2008 Jan; 32(1):160-5. Epub 2007 Oct 9.