Vegan eating
What it is
Eating without any animal product — no meat, fish, eggs, dairy or honey. A pattern chosen almost always for ethical or environmental reasons, and one where the nutrition has to be done on purpose: some nutrients simply do not have a reliable plant source.
How it works in practice
Legumes, soy in its many forms, grains, nuts, seeds, vegetables and fruit, with fortified foods for what plants lack. Vitamin B12 is the non-negotiable: there is no dependable plant source, deficiency is slow and serious, and a supplement or fortified food is part of the diet, not an extra. Protein needs legumes, soy or grains at every meal to reach the target for weight loss; iron, calcium, iodine and omega-3 fats each have a plant route that has to be chosen rather than assumed.
What the evidence shows
In the meta-analysis of vegetarian diets, the vegan arms showed the largest weight effect — on the order of two and a half kilograms more than comparison diets over a median of eighteen weeks. The review attributes this to energy density and fibre, the same mechanism as for the other vegetarian patterns, only stronger because the exclusion is wider. It is a short-term signal from short trials, with dropout in the vegan arms a recognised problem; it does not speak to keeping the weight off, and it does not show that the exclusion itself removes fat.
Who it tends to suit
People who have already chosen it for other reasons and are asking whether it can carry a deficit (it can, with planning); people who like cooking and legumes; people for whom the ethics make the practical friction worth it.
How it most often fails
Nutritionally, on B12 and protein, quietly and slowly. Socially, at every table that is not their own — the pattern has the highest practical friction on this site. And on the scale, through the same route as any other pattern: nuts, oils, pastry and processed substitutes are vegan and dense, and "plant-based" is not a deficit.
What to watch
B12 first, always. Then protein per meal — the protein calculator gives the figure, and reaching it from legumes and soy is the daily task. Iron and calcium for women in particular. And, for anyone with a history of restriction, the honesty to notice whether the exclusion is serving the ethics or the restriction.
In the app
The vegan policy code exists and the planner takes it into account, but its revision has no documented review yet, so the app treats it as context rather than a verified rule — and it does not plan supplements, which remain your own routine in the account.