The Dangers of Sugar

There’s a YouTube video I strongly recommend all personal trainers in London watch several times over and take careful notes, then pass on the information to their clients. It’s called “Sugar – The Bitter Truth” by Robert Lustig.

Robert Lustig MD is on a mission to educate the world about sugar. He is an endocrinologist (an expert on hormones and in particular, in Robert Lustig’s case, the hormones which influence your metabolism) . He is also Professor of Clinical Paediatrics at the University of California, San Francisco (UCSF), specializing in childhood obesity.

Is obesity down to genetics?

I was the personal trainer in Chelsea to an overweight client whose kids were overweight too. He was convinced that obesity was genetic, and that there was little to be done. “Look, my kids are overweight too,” he would say, “they’ve inherited my fat genes.” While genetics may play some small part, lifestyle choices are the dominant factor.

If it were genetics, why has obesity rocketed in the last 40 years? Evolution doesn’t work that fast, it’s very slow in causing physical changes to a species in tiny increments over hundreds of thousands of years. What’s changed in the last 40 years is the rise of the junk food industry, this is the single biggest factor.

According to Robert Lustig (and mountains of supporting evidence) sugar, ie – sucrose and high fructose corn syrup, are the leading cause of obesity and type 2 diabetes worldwide. He illustrates that sugar is found hidden in the most unlikely places: wholemeal bread, organic low fat yoghurt, Slimfast drinks (and practically all commercial diet food products), even leading brands of baby food.

The addition of sugar in baby food by manufacturers is a particularly cunning ploy by the junk food industry, which is keen to get as many people addicted to sugar from as early an age as possible, in order to win lifelong devotees to junk food and ready meals.


One major problem with sugar is that it creates leptin-resistance in the body. Leptin is the hormone generated from your fat cells which signals that you’re full. It’s the ‘feel full’ hormone. Sugar suppresses this hormone, and as a result you over-eat processed foods. Lustig says: “today’s biochemical negative feedback system is damaged.” Damaged by what? By sugar.

On a public health policy level Robert Lustig is quite clear: sugar is a toxin, and should be taxed and regulated in the same way as tobacco and alcohol.

Further viewing on YouTube:

The 2013 Dolan Lecture: Robert Lustig
Sugar – the elephant in the kitchen (TedxBermuda2013)