A new book outlines an experimental food plan tailored to your body.

We’re mere days into the new year and, though you may already find yourself knee deep in the ascetic mire of paleo and ketogenic diets, Veganuary, alcohol abstinence and intermittent fasting, you may want to put down that handful of almonds intended to suppress your Snickers craving, and wrap your chops around this. According to two Israeli scientists, Professor Eran Segal and Dr Eran Elinav, successful diets don’t depend on foods at all; they depend on people. “Every food affects every body differently… What if each person requires a different diet tailored to his or her own body composition?” they write in their book The Personalized Diet, which is based on an extensive study, the Personalized Nutrition Project, which “we believe has the potential to shift the very foundations of nutrition science”.

The key to their research doesn’t involve as much sweat and tears as most transformative diets, but it does involve some blood. Blood glucose levels, to be precise, and recording them after every meal (you can pick up a monitor relatively cheaply from your local pharmacy or drug store). Monitoring your blood sugar levels for a month, the scientists argue, will allow you to identify which foods spike your insulin levels the most and therefore put you more at risk of metabolic diseases such as diabetes. By avoiding these foods, you should lose weight. In the book, one subject finds that sushi and fruit salad spiked their blood sugar levels more than wine and chocolate. Unfortunately, this doesn’t mean you can live on Malbec and Mars bars. “If you take in a lot more energy than your body needs, regardless of blood sugar, you will store that extra energy as fat,” say Professor Segal and Dr Elinav. But it does mean certain foods will give you more energy for their calorific buck. See below for their key tips for tailoring your diet.

Draw up a meal plan based on your results

After testing your blood sugar after meals, it’s time to separate foods into good and bad categories. “Include the meals and foods that did not give you a blood sugar spike or that you were able to modify to eliminate an initial blood sugar spike,” they write. It’ll take a bit of time, but once you know which foods work for you, you can compile a meal plan. “This should be completely individual to you, considering what you like, how often you like to eat, how much food you need and other factors, including what foods are in season, within your budget and so on.” Happily for the epicureans among us, the personalised diet is not as stringent as most, and experimenting is all part of the fun. “The world is filled with thousands of different foods, and they can be grouped into endless combinations that might be good for you, enjoyable and blood-sugar stabilising. Keep testing, keep trying new things and be a food adventurer,” say Professor Segal and Dr Elinav.

Calories aren’t king

Nutrition, diet talk and insufferably ubiquitous “life hacks” are often so rife with pseudoscience it’s hard to know what to believe. “While the old adage ‘calories in, calories out’ is still used as a weight-loss method, science has debunked this oversimplified notion that all calories operate the same in the human body,” write the authors. “Different people have different amounts of energy available for digestion, and efficiency varies with different people. A calorie counter could never account for all these individual variables.” In other words, agonising over how many calories are in certain foods may not be the most productive use of your time, because everyone is different. Instead, concentrate more on things that don’t spike your blood sugar as much, and get more sleep, which, the authors say, helps keep blood sugar levels in check.

But do monitor your portions

Once you’ve found what works for your personalised diet, avoid binging. “Eating too much, even of foods that do not spike your blood sugar when eaten in moderation, can cause blood sugar spikes in some people,” say the authors. “Regularly overeating can also mean you are taking in more energy (calories) than you need and, over time, this will almost certainly result in weight gain.” In other words, even if you find that, say, a Sunday roast doesn’t disrupt your blood glucose too much, that doesn’t give you a free pass to wolf down as many Yorkshire puddings as you can. Keep portions balanced and consistent to keep your initial blood glucose readings as accurate as possible.

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