Monodiets and fasting: the forum debates eating less to live longer

Fasting and monodiets: eating less to live longer

Three kilos of Golden Delicious apples in a single day. The next, two kilos of pineapple. And after that, a kilo of minced beef cooked in its fat, with two litres of green tea alongside. These are experiments someone claims to have tried on his own body and from which he draws an uncomfortable conclusion: eating less, and eating more simply, makes you feel better and, he argues, keeps premature death at bay. Whoever raises it warns from the outset that he is not a doctor or nutritionist and that all this is, in his own words, “know-it-all experiments”.

What you eat when you eat little: monodiets and three-day fasts

The starting point is that the human body is not made for dishes with seven or eight ingredients. A breakfast of pastries with torrefacto coffee, a lunch of pork fillet with alioli sauce, fries, salad and cheesecake, and a late, heavy dinner: that accumulation, he argues, takes its toll from age 30. The alternative he proposes is the monodiet: a single food, in unlimited quantity, for a whole day. And if that isn't enough, fasting. Three days without solids, with a maximum of 200 calories a day in the form of consommés and broths, plenty of green tea, walks on the beach, naps and 12-kilometre walks. The condition for it to go well, he adds, is having no one nagging at home and no boss waiting for results.

“You are not what you eat, but what you assimilate”

The argument that gets the most traction is that of digestive incompatibility. Mixing different foods in the same sitting, it is argued, complicates digestion and ruins absorption. The formulation is blunt: you are not what you eat, but what you assimilate, and a mixture is assimilated very poorly. Hence the example of milk with cola, offered as a home test of what happens when you combine things the stomach processes at different speeds. None of those who support this thesis cites a study to back it up; the argument rests entirely on personal experience.

Intermittent fasting 16/8: fewer hours, not less food

The least aggressive version of eating less has a name and a schedule: 16 hours without eating and an 8-hour window, known as 16/8. It is explained like this: when the liver's glycogen is depleted, the body starts using its own reserves, and the first thing to go is abdominal fat. Someone who has practised it several times describes it as an easy method to sustain because it doesn't ban foods, it only narrows the clock. The approach itself specifies that within the window you can eat “whatever you want without overdoing it”.

From 89 to 73 kilos without sugar or processed foods

Here the thesis stops being an impression. A specific case: from February to date, from 89 to 73 kilos, with no chocolate, no beer —the one he drank was alcohol-free—, no nachos with guacamole, no croquettes and no bread and butter. Two weekly 40-minute sessions on an exercise bike as the only exercise. The menu still includes burgers and pasta with cheese, and the stated goal is between 1,700 and 2,000 calories a day. Breakfast is reduced to fruit. His reading is that the problem is not quantity but content: people who overeat tend to eat cheap, ultra-processed products.

Those who eat cookies and make it to 97

Any thesis about extending life runs up against the cases that disprove it. A woman is cited who at 94 ate cookies, sweetened yogurts and chocolate every day, with a stew at midday, and who now, at 97, is still alive, and her sister, 95, in the same care home. And earlier generations who ate bread, bacon, wine and tobacco and reached 90 without a problem. The explanation gaining weight is not diet: genes matter, and the physical work of getting up early and moving all morning did the rest. The statistical correction comes from another poster: you only see those who survived, not the siblings who fell by the wayside. In an era when having five or six siblings was common, one or two reached old age.

The energy expenditure that no longer exists

The other half of the problem isn't eaten. The reasoning is that an office body—sitting, snacking and shut behind four walls—cannot assimilate the same as a body that works ten hours in the fields. It is noted that some people compensate for that lack of expenditure with strength training and walks, and avoid overdoing prolonged aerobic exercise because it burns muscle and lowers metabolism again. The consequence pointed to is social, not individual: a life of restaurants, buffets and set menus, with hotel breakfasts that, adding lunch and dinner, can be around 4,000 calories, is the perfect scenario for getting ill.

BMI, B12 and the loose ends no one ties up

Here the conversation forks. On one side, someone argues that obesity cannot be defined by body mass index, because not all bodies have the same hips, and that there is no obesity gene. On the other, someone who gives up meat and takes vitamin B12 because, he claims, a deficiency causes neuritis and cramps, although his blood work comes back impeccable except for underlying Hashimoto's. And in the middle, the shared suspicion that gym-built muscle with 6% body fat is not a healthy body, only a healthier one than an obese body. All of this comes from personal experience and none of it is accompanied by a study.

With this, the matter ends up exactly where it began. No one offers a clinical trial, cases of longevity are explained by genes or luck, and the only available evidence is the very body of the person telling the story. Eating less seems to work. Why it works remains unanswered.