I’ve learned a lot in 50 years, enough to make me cautious giving anyone nutrition advice. My area of expertise is sugars and starches. In the 1970s, we saw that milk drinking wasn’t ideal for everyone. Genetically determined lactase insufficiency was the norm past childhood and only some Europeans and their descendants were exceptions. Textbooks informed me that starches were digested slowly, while sugars were digested quickly. This was the reason for restricting sugar intake in people with diabetes. In 1981, that idea was overturned by David Jenkins’ research on the glycaemic index of foods. On average, starchy foods such as potatoes, breads, rices and breakfast cereals produced higher blood glucose responses, gram for gram of carbohydrate, than sugary foods. For years, sugar was off the hook, although the pendulum swung back in the early 2000s. The prevalence of obesity had surged in the 1980s and with it the idea that sucrose and fructose were particularly obesogenic. We were told that fructose, unlike glucose, was metabolised in the liver and easily turned to fat. Sugar and sugar-sweetened products became dietary demon #1, displacing saturated fat from the top spot. SSBs were particularly troublesome and low joule sweeteners flooded the market. In Australia, one in two soft drinks were low joule. But when Alan Barclay and I showed that sugar intake and SSB consumption in Australia had declined over the same timeframe that obesity had tripled (the fastest rate globally), we were scorned. New research would show that fructose was converted to glucose in the gut mucosa and only unphysiological doses were a problem. Today, research shows that sugars bankrolled early human evolution, contributing >25% of energy for >3 million years.