But such a substance exists, explains consultant bariatric surgeon Andrew Jenkinson, and every one of us uses it many times a day.

“This elixir of life already exists – it is called food,” he says. “But be warned, the door can swing the other way too – this same ‘drug’ can also cause weight gain, obesity, diabetes, inflammation, allergies and misery.

“Like any addictive drug, it can interfere with your reward pathways, make you feel unnaturally high, and lead to addictions and the formation of bad habits – and those bad habits and that unhealthy body become you.”

Despite many people’s obsession with counting calories, Jenkinson, who specialises in weight loss surgery and laparoscopic procedures in London’s Harley Street, believes calories are less important than what food does to your body and brain. He’s adamant that if people treated food as a drug, where certain foods are considered ‘toxic’ and others ‘medicinal’, they would be able to lead a healthier lifestyle far more easily.

“The calories in your food are of secondary importance to your weight and health,” he insists. “It’s what the food does to your body, and just as importantly what it does to your brain, that matters.

“Once you grasp that food works just like a drug, and that the drug can be either medicinal or toxic, your whole outlook on food will change. Armed with this knowledge, you will have the keys to unlock a healthier life, without needing to resort to willpower, because once you understand how food affects you, you will naturally start to crave good food.”


What to eat less of

High sugar and refined carbohydrates

Jenkinson explains that leptin, a hormone produced by fat cells, is crucial for maintaining a healthy weight as it increases metabolism and decreases appetite. But people who are obese can develop inflammation, which stops the leptin doing its job, leading to leptin resistance.

Certain foods containing high sugar and refined carbohydrates are what Jenkinson calls leptin busters. “These block healthy leptin signalling, leading to weight gain,” he says. “Leptin busters are any foods containing large amounts of sugar and highly refined carbs, including cakes, pasta and bread.”

Sweetened soft drinks

Fructose is a naturally-occurring sugar found in fruits, honey and many other plant foods, and it’s often added to processed foods and sweetened soft drinks. Jenkinson says if a lot of fructose is consumed, it can trigger a weight gain signal within cells.

“This newly-discovered primitive response would normally remain dormant unless very high quantities of fructose are sensed,” he explains. “But these high fructose concentrations are found in processed foods – flicking on the fructose switch and leading to weight gain.”

Fast food and processed foods

Processed foods are designed to stimulate very powerful feelings of reward and pleasure when eaten, and this makes our brain want them over more natural foods, says Jenkinson.

But such foods are full of vegetable oils, he warns. “Although we’ve been reassured by nutritionists that these oils are healthy, they are in fact hazardous to the delicate balance of the important omega fats that bathe our cell walls.

“Too much omega-6, a nutrient found in massive excess in these oils, dilutes the health-giving effect of omega-3’s. Omega-6 causes malfunctioning of our insulin signals, meaning we need more of it, and leading to the same effect as taking in too much sugar.”

He says too much omega-6 also triggers inflammation, which increases the risk of becoming unwell or developing an inflammatory disease. Foods containing these omega disruptors include fast foods, crisps, processed foods with a long shelf life, any food cooked in vegetable oil (sunflower, canola, rapeseed etc.), egg yolk, and farm-fed chicken and pork.

Food containing artificial colourings and flavouring

Most colourings, flavourings, emulsifiers and other artificial food additives “are not, and have never been, food” stresses Jenkinson. “They are chemical elements that have been designed in laboratories for the benefit of food companies.”

He says some have been shown to cause inflammation, severe allergies and increased risk of cancer, and points out that most processed foods contain them. “So avoid these where possible. They act like a toxic drug.”


What to eat more of

Fish

Fish is full of omega-3 oils and therefore it’s anti-inflammatory and helps weight loss, says Jenkinson. “Sushi is great – the Japanese, who eat a lot of it, are some of the healthiest people in the world.”

Credits: PA; Author: PA;

Egg whites

Egg whites are a great protein source, says Jenkinson, who advises people to eat them in order to reduce the level of omega-6 found in egg yolks.

Healthy grains

If you’re trying to lose weight, be conscious of consuming too many carbs in the form of white rice, potatoes and bread, Jenkinson warns, and instead choose pulses and beans, quinoa or buckwheat, which don’t spike your insulin levels.

Leafy greens

Eat fresh vegetables, particularly leafy green and brightly-coloured ones, as these infuse your body with phytochemicals, which are anti-inflammatory, as well as antioxidants, Jenkinson advises. “If you take in most of your carbs through vegetables, your weight-control hormone will keep on functioning normally, meaning no weight gain,” he notes.

Berries

Berries are full of phytochemicals and low in fructose sugar. High amounts can trigger our body’s hibernation state, leading to weight gain, explains Jenkinson.

Saturated fats

According to Jenkinson, research now shows it’s fine to eat fatty steaks, red meat (grass-fed for healthy omega-3), butter and yoghurt, but avoid palm oil, which has links to heart disease.

“Red meat is not bad for you,” he insists. “It is full of health-giving natural saturated fats. These fats do not spike insulin levels and do not cause obesity.”

Natural spices and salt

Unless you suffer with high blood pressure then salt can be used to season meat and fish before cooking, says Jenkinson. “This brings out fantastic flavours in home-prepared foods,” he explains. Keep your pantry full of flavoursome and aromatic spices and herbs to make meals something to savour, he advises, adding: “Your natural spice rack is a nutritional powerhouse containing minerals, vitamins and those important anti-inflammatory phytochemicals.”

How to Eat (And Still Lose Weight) by Dr Andrew Jenkinson is published by Penguin Life