One week butter is good for you, the next, bad. The same with meat. While physician, author and BBC TV regular Dr Rangan Chatterjee finds emerging new science fascinating, he advises some caution when it comes to dishing out nutritional advice.

“If you’re under the impression that there’s one perfect diet that’s going to help you, I’d invite you to think again,” he says. “Different things work for different people.” 

Instead of telling us what we should or shouldn’t be eating, Dr Chatterjee has some clear principles to help guide you through the confusing nutritional information out there. 

These five pillars of good diet form part of his new BBC Maestro series. Two decades of seeing tens of thousands of patients and he knows what practically works for busy people with busy lives. 

There’s also a host of different factors that will influence your personal nutrition, says Dr Chatterjee: for instance, your previous relationship with food, your heritage, how many antibiotics you’ve taken in your life that might have affected your microbiome, and therefore how you process and metabolise food.

“What these principles give you are the very solid foundations of the small things you can do every day that really do make a difference to your health and your happiness as well.”

Reset your relationship with sugar

You do not have to stop eating sugar. “That is frankly unrealistic for most people, nor do I think most people need to do that,” says Dr Chatterjee. 

Humans are biologically wired to crave sugar. And there’s a good reason for that. “We’ve got to remember that the ability to take sugar in and store it as energy, as fat, is frankly a super power for humans. It’s what allowed us, depending on where we were in the world, to get through winter.”

The problem is that, in the modern food environment, we are tempted by low-quality foods that are high in sugar everywhere we go.

The first sugar pitfall to look out for, says Dr Chatterjee, is hidden added sugars. “If you eat meat you may be surprised if you flip over a packet of ham or chicken breast and see that sugar is one of the first ingredients. This is why people are struggling so much, because a lot of us have conditioned our taste buds to want sweet things. And therefore food manufacturers want to make things that people like and will buy more.”

Eating an unprocessed diet will eliminate many hidden sugars. When it comes to fruit, Dr Chatterjee says the sugar in an orange is fine when eaten with its natural fibre. The problem comes when you have it as juice.

This can be the sugar of, say, six oranges without any of the fibre. “Then you’re mainlining sugar. It’s fine as an occasional treat but you wouldn’t want to have that everyday.”

The second sugar pitfall is eating foods that rapidly convert to sugar in our blood. 

“A lot of ultra-processed foods are full of refined carbohydrates, and the problem with these is that if, you have them for breakfast, it can put you on a blood-sugar rollercoaster all day.”

Dr Chatterjee had a patient who ate granola for breakfast thinking it was a healthy choice. “By the afternoon he was tired and struggling to concentrate and craving sugar.”

Dr Chatterjee suggested he try eating his dinner for breakfast instead. Switching to a savoury start to the day quickly made him feel better, and helped him lose the extra weight he wanted to. 

“If people can eat in a way that starts to stabilise their blood sugar a lot more they just effortlessly have more stable moods, fewer cravings and more energy.”

Be good to your gut bugs

Until 10 years ago modern science wasn’t really aware of the gut microbiome. “Now we have what frankly seems like a new organ that lives inside us,” says Dr Chatterjee.

The collection of bacteria, viruses, fungi and their genetic material that make up a healthy gut microbiome is linked with good health in many different areas of the body. While a disrupted microbiome has been linked with problems with your gut and digestion, but also low moods and the development of neurodegenerative and auto-immune diseases like rheumatoid arthritis.

Even your weight is related to the health of your gut bugs. “This is an exciting, burgeoning field of research and we don’t know everything yet,” says Dr Chatterjee. “However, we think a healthy microbiome is likely to be a diverse one.” 

Trying to eat 30 different types of fruit, veg, pulses, wholegrains, spices, nuts and seeds a week have been recommended. However Dr Chatterjee worries that even the recommendation to eat five different coloured vegetables a day can be off-putting for people. 

“Some people can’t tolerate that. Even if you build up slowly you’ll get bloating or stomach ache.”

Trying fermented foods, such as sauerkraut, kefir or kimchi instead can be a starting point. “Eat a spoonful of sauerkraut each day. Or, if you eat dairy, have some live yoghurt. All of that will help your gut microbiome.” 

Pay attention to when you eat

Intermittent fasting is all the rage. But should our eating window be eight, 10 or 12 hours a day? It can be confusing. And what even is the point?

Dr Chatterjee wants us to take a step back and look at the bigger picture. “We are not designed to eat continuously. Professor Satchin Panda did some research a few years ago showing that over 50 per cent of Americans were eating over a 15-hour period each day. Most humans on the planet 50 years ago were probably eating in a 12-hour window, which allowed all the housekeeping processes to kick into gear in our body overnight.”

“Food” includes the milk or sugar in your coffee first thing in the morning, and of course that packet of crisps in front of the TV at 10pm. For many years Dr Chatterjee has been recommending at least a 12-hour window of not eating. “Around 95 percent of my patients can do it. It means breakfast at 8am and you finish dinner by 8pm. Or 9am till 9pm. Whatever works best for you and your lifestyle.”

The science behind the benefits is still emerging but early data is showing that, when we eat in a fixed eating window and we keep some regularity with eating patterns, it can potentially help with weight loss, better blood-sugar control and better immune-system function. 

“I have also seen, with hundreds of patients, that it can help with things like cravings and irritable bowel syndrome,” says Dr Chatterjee. “Often you find those symptoms get much better because you’re eating with your natural circadian rhythms.”

Unprocess your diet

This is his most important principle when it comes to nutrition. While it’s possible to lose weight on an 800-calorie-a-day diet of junk food, that isn’t good for overall health. 

“Most people who want to lose weight also want to do so and be in good health,” says Dr Chatterjee. “And that’s where the quality of your food really matters.”

Sticking to mostly unprocessed whole foods that are close to their natural form has the power to make you feel less hungry, feel less tempted to eat what Dr Chatterjee calls ‘blissy foods’ (“foods with devilishly blissful combinations of salt, sugar and fats within them, which frankly no human can resist”) and will allow your body to manage your weight for you, rather than you having to actively do it. 

“When you eat whole foods there are beneficial effects on inflammation, on your immune system. These are essentially the foods we’ve evolved to eat. That our grandparents were eating. Only in the past 20 years have we had this explosion of food products as opposed to food.”

So how do you identify processed food? “A very simple rule of thumb that I’ve found to be useful is if something you’re buying has more than five ingredients in it, there’s a pretty good chance that this will be an ultra-processed food product.”

Know why you eat

The truth is that many of us know what sensible eating involves. We know what’s healthy and what we should be eating, and yet we still struggle. 

That’s because, says Dr Chatterjee, the problem is a lot of the time we are not eating because we’re hungry, but for other reasons.

“I say we often eat to fill a hole in our heart, not a hole in our stomachs these days. We eat when we’re lonely, tired or stressed or we’ve had a row with our partner. It’s comfort eating.  I’m not blaming anyone. I also do that.”

If we do want to eat differently then we need to ask ourselves, why is it that we are consuming the foods that we say we don’t want to consume? “You have to do this compassionately and not tell yourself off,” says Dr Chatterjee. 

The “3Fs” is an exercise he likes to do with patients. They stand for: feel, feed, find.

“When you’re on your sofa at 9.30pm and it’s rainy, windy and dark and you feel like having ice cream, first feel. Take a pause and ask yourself what you’re really feeling. Is it physical or emotional hunger?”

The second F is feed. “Now you’ve identified the feeling. How does the food feed the feeling?” The third F is find. “What alternative could feed that feeling?” 

Instead of ice cream, could you run yourself a bath? Or, if it’s loneliness, instead of a glass of wine, maybe you could phone a friend? “It’s a very simple exercise that helps us to start to figure out why we’re making these choices.”