What you lose by feeding yourself with a "meal-replacement drink"

In the article "No more food: how to feed yourself with a cocktail", which we published last March 18, we find a series of pieces of information that are obvious to anyone interested in food and artificial nutrition, but that easily risk leading to simplistic conclusions.
If we instead analyze more carefully what is presented on the site http://robrhinehart.com, the experience described also lends itself to interesting considerations from a scientific point of view.

A BIT OF HISTORY
It is common knowledge that humans "eat foods but use nutrients" after having digested and absorbed the former. On this basis, even before the First World War, studies were begun on animals to identify their nutritional requirements by preparing experimental diets from purified foods; during the Second World War (1942, Mead Johnson) the first diets with a defined chemical composition appeared (in which all the nutritional components were chemically defined and purified), up to the long-term human studies with such diets (Winitz) dating back to the 1960s and sponsored by NASA.
Currently, liquid "formula diets" are available, or also with a modified consistency for subjects who may have swallowing problems (dysphagic), usable in practically any physiological or pathological situation. There are also studies available demonstrating the possibility of long-term use without the onset of deficiency or excess pathologies.

A DESCRIPTION
Soylent, in some respects comparable to a "formula diet", also contains substances not normally present in formula diets, as they are not considered essential to physiology but that may lend themselves to interesting interpretations regarding the sense of well-being that —according to the author— this "meal-replacement drink" is able to stimulate. We are talking, for example, about lithium, which, according to some studies, would be the best mood stabilizer available and a true neuroprotector against the damage caused by bipolar disorder. Obviously we are in the realm of hypotheses, but the idea is intriguing.

SOME MEDICAL CONSIDERATIONS
The article speaks of a low-calorie diet for the sake of greater longevity (demonstrated for single-celled organisms and rodents but not for humans or primates), but the final formulation used by Rob contains 2629 kcal, which—assuming a standard consumption of between 26 and 30 kcal per kg—puts the weight of our "nutritional chemist" at between 87 and 101 kg.

The distribution of macronutrients is in line with the indications of a healthy and proper diet: 62% carbohydrates, 22% fats (largely from olive oil) and 15% proteins. Minerals and vitamins are all well represented, and the antioxidant intakes are important; what is completely insufficient, on the other hand, is the presence of dietary fiber (1.2 g/day), which suggests problems with intestinal function that can only be detected over time (not in the short term, like the 30-day follow-up carried out so far). Ultimately, we might consider that we are looking at a nutritional proposal that is sufficiently hygienic and adequate.

What is instead completely missing is the cultural, social and hedonistic aspect of eating, which in this experiment is reduced to a simple supply of the substances indispensable to keeping the body functioning. A view of nutrition defined in this way could easily fall among the new eating-behavior disorders (not yet present in the DSM), specifically orthorexia. Reading the blog, however, one understands that, even while consuming 92% of his requirements in the form of Soylent, Mr. Rob Rhinehart admits his desire to occasionally have dinner with friends and to enjoy a good breakfast when he wakes up early.

Finally, the hypothesis of being able to defeat obesity through behaviors that, by his own admission, are antisocial and —therefore— difficult to sustain over time, seems rather utopian, barring eating-behavior problems as already mentioned earlier. It seems frankly optimistic, in this economic climate, the cost calculation made by Rhinehart, who claims to be able to nourish himself and stay well on 159 dollars a month plus the shipping costs of the products (the proteins being especially expensive).