Iain Campbell was gazing out the bus window on his way to work when he first sensed something radical was reshaping how he experienced the world.
The inkling emerged from an altogether ordinary observation: He felt peaceful, maybe even happy as he watched the trees along the road pass by.
“I hadn’t experienced that in a really long time, probably since I was a kid,” says Campbell, who lives in Edinburgh, Scotland.
“I didn’t know what was going on at the time, but I thought this might be what it feels like to be normal.”
Campbell had lived with bipolar disorder for much of his life. Mental illness runs in his family, and he’d lost loved ones to suicide. Over the years, he’d tried different treatments, but it had become “increasingly difficult to live with.”
What had changed? A few weeks earlier, he’d started a new diet.
Campbell dealt with unwanted weight gain and metabolic troubles, a common side effect of psychiatric medications.
To lose weight, he tried to drastically cut back on carbs and instead focus on protein and fat. It turns out he’d unknowingly entered ketosis: A metabolic state where the body switches from glucose as its primary energy source to ketones, which come from fat.
He started learning about the ketogenic diet, which is high fat and very low carb, on podcasts and YouTube videos. Soon, he was tracking his ketone levels, courtesy of an at-home blood test.
“I realized it was actually the ketone level that was making this shift in my symptoms in a way that nothing else ever had,” he says. “It struck me as really significant, like life-changing.”
A career-launching moment
How exactly was a diet performing this alchemy? Campbell decided to pursue a PhD in mental health at the University of Edinburgh, hoping to do his own research and learn if it could help others.
In online forums, people with bipolar disorder were sharing similar anecdotes — they were finding improvements in their mood, increased clarity and fewer episodes of depression.
But as Campbell searched for ways to launch a proper clinical trial to test the diet’s effectiveness, he became increasingly…