On a recent trip to London, I visited my grandparents’ graves at Willesden cemetery. Strolling through the grounds, I spotted the tombstones of friends and relations who had played formative roles in my childhood. But as I read the inscriptions on the graves, I was shocked to discover how young these people were when they died. 

Thankfully, improved medicine, hygiene and diet means that people are now living a lot longer. But all of that could change. With a quarter of British adults obese, we’re carrying a sugar-coated death sentence and the nation’s health is at risk. Religion and fitness can go together. But are the rabbis promoting it?

We know from debates around smoking that rabbinic opinion adjusts according to medical advances. Smoking which was once acceptable in halachah is now prohibited by many leading rabbis. But food for Jews is always complicated. It’s been suggested that “religious cooking is generous cooking”, which sounds attractive, but today we know that “generous cooking” can kill us. 

One yeshivah published its response to an anxious student, who asked how to balance his health requirements with the rules of etiquette when he is bombarded by oversized portions dished up by a parade of well-meaning Jewish families who host him for Shabbatot.

The Torah repeatedly commands us to guard our souls (Deuteronomy 4) and the rabbis understood this to imply an obligation to look after our health. The Rambam in particular wrote extensively about the need for moderate eating and regular exercise. He felt these were important spiritual values because we should look after the body that God has given us. Moreover, to live the fullest possible spiritual life, we need to be as healthy as possible. Finally, the Rambam saw an ethical obligation to live a life of moderation, abstaining from over-indulgence. 

Perhaps, it’s never been harder to stick to the Rambam’s recipe for healthy living. Today, our supermarket shelves are stacked with foods that are full of salt, sugar, fat and preservatives. Observant Jews must not only ask what’s kosher, but also which foods meet our dietary requirements for wellbeing. Fortunately, guidance is at hand. Eliezer Melamed is a contemporary Israeli rabbi whose series of books Peninei Halachah courageously define halachah for our times.

Rabbi Melamed stresses we should make every effort to eat healthily, avoid unhealthy food and educate others to do so too. But he admits this is not always simple since medical advice is constantly changing. Foods that were once considered unhealthy are now deemed acceptable, whereas foods that we thought were healthy turn out not to be. Despite this baffling situation, he recommends those wishing to meet the requirements of halachah follow current mainstream medical opinion. 

In setting out his approach, Rabbi Melamed acknowledges that there are many other factors that a rabbi must consider when making a halachic ruling. This is particularly relevant to his discussion of junk foods. The rabbi recognises that even foods which are not good for us won’t do great harm if they are eaten by healthy people in moderation. We all like the occasional treat, so he’s reluctant to place a blanket prohibition on them. More significantly, his reluctance to ban junk food stems from a sense of responsibility to those on modest incomes. 

Healthy eating is expensive and if he were to prohibit eating convenience foods, he fears that some poor people would go hungry rather than disobey. The resulting deprivation would create unreasonable suffering which might lead to even worse health complications. Finally, Rabbi Melamed suggests that people who are used to eating processed foods might react badly to going cold turkey which could lead to depression with its own formidable dangers.

While Rabbi Melamed is cautious about issuing an absolute prohibition on junk food, there are times where common sense and halachah demand drastic action. Where patients have been warned by their doctors that eating certain foods will kill them, he rules that these items no longer “kosher” for them. If they do succumb to temptation, the patients are sinning and they may not recite a blessing over these items since you don’t thank God for foods that poison your body. In a more conciliatory note, the rabbi advises those of us who are just overweight to diet with moderation because extreme dieting can be miserable for the mind and bad for the body.

It’s vital for rabbis to promote healthy lifestyles, but our sages were also withering about hypocritical teachers who “preach well, but do not live up to their own words”. Since I probably fall into that category, I am going to clamber off my couch and head for the gym now. Bon appétit!

Gideon Sylvester is the United Synagogue’s Israel Rabbi