So, what is this diet? It largely looks like what you know about eating healthily – high in fibre, rich in fruit and vegetables, low in added fats and sugars – but Dr Greger says, even as an expert in clinical nutrition, he was surprised to learn that some foods affect weight gain.
“You often hear about salt as being bad for blood pressure, but it’s also an appetite stimulant,” he says. “It digs into our evolutionary drive; we’ve evolved in a time of calorie scarcity.”
Not that we shouldn’t eat any salt. With the exception of some weight loss methods (“it’s about healthy weight loss … you could try water-only fasting but it’s guaranteed to kill you in a number of months”) Dr Greger rarely rules out a method of eating, instead recommending moderation and consideration, as well as thinking about why you believe something will make you lose weight: is it because someone is trying to sell you something?
A great example, he says, is chronobiology, a guiding principle of eating that is definitely less well known than “paleo” or “juice cleanse”, but has plenty of science behind it.
Chronobiology is the branch of biology which concerns our body’s rhythms and how they affect our health i.e. how our circadian rhythms might affect our ability to respond to chemotherapy, to concentrate or lose weight.
“It is about the role the time at which something occurs has on its effectiveness,” Dr Greger explains, noting that one of the best tips he can offer someone looking to lose weight, based on the research that has been done, is to make breakfast their main meal.
“The food industry is based on the idea that calories are calories,” Dr Greger explains. “But the calories you eat in the morning do just result in less body fat than those you eat later in the day, and not just because people are mindlessly snacking on the couch at night.
“But why don’t many people know about this? It’s because you can’t make money from it.”