Diets · honest read
Vegan
Everything animal-derived off the plate - and everything that decision asks of you in return.
carbs 45–55% · protein 15–20% · fat 25–35% of calories · daily fiber target
What it is
A vegan diet excludes every animal-derived food: meat, poultry, seafood, eggs, dairy, and animal byproducts such as gelatin. What remains is the entire plant kingdom - vegetables, fruits, legumes, whole grains, nuts, seeds, and soy foods like tofu and tempeh. Built on those whole foods, the macros naturally land moderate: roughly 45–55% of calories from carbohydrate, 15–20% from protein, and 25–35% from fat.
People arrive at veganism for different reasons - ethics, environment, health - and this page covers only the metabolic-health side. That side has one defining feature worth stating up front: "vegan" describes what a diet excludes, not the quality of what it includes. French fries and soda are vegan. The health results people associate with the pattern come from the whole-plant version of it, not from the label.
That makes this one of the more demanding diets to do well. It is the only common eating pattern with a truly mandatory supplement - vitamin B12 - and protein, iron, zinc, calcium, and iodine all need more deliberate attention than an omnivorous eater ever gives them.
How it works day to day
A well-built vegan day is anchored in legumes: lentils, chickpeas, black beans, tofu, tempeh, edamame. Protein needs deliberate pairing - legumes with grains, nuts, or seeds - because most single plant foods are lighter in one or another essential amino acid, and because plant protein sources bring carbohydrate and fat along with them. Hitting 15–20% of calories as protein is entirely doable, but it does not happen by accident.
B12 supplementation is non-negotiable, since no unfortified plant food supplies it reliably. Beyond that, day-to-day practice means favoring iron- and zinc-rich foods (legumes, seeds, whole grains) with vitamin-C-rich foods to help absorption, finding calcium in fortified plant milks and leafy greens, using iodized salt or another iodine source, and getting omega-3 fats from flax, chia, hemp, and walnuts.
The everyday trap is the refined-substitute aisle. Vegan burgers, cheeses, and desserts make the transition easier, but a diet built on them is a refined-food diet that happens to contain no animals - and the metabolic advantage disappears with the whole plants. Most experienced vegans treat substitutes as occasional convenience, not foundation.
Advantages
Reliably lowers LDL cholesterol
This is the pattern’s best-documented effect. Randomized trials consistently show that vegan diets lower LDL cholesterol compared with omnivorous eating, driven by the removal of most saturated-fat sources and the fiber and plant sterols that replace them.
Fiber intake most eaters never reach
A whole-food vegan diet routinely delivers double the fiber of a typical Western diet, simply because every calorie source is a plant. That shows up as steadier glucose responses to meals, better satiety per calorie, and a gut microbiome fed the way it evolved to be fed.
Associated with lower cardiovascular and diabetes risk
Large observational cohorts, including EPIC-Oxford and Adventist Health Study-2, associate vegan eating with lower rates of ischemic heart disease, hypertension, and type 2 diabetes. These are associations rather than proof - the people are unusual along with their diets - but they point the same direction as the trial evidence on cholesterol and blood pressure.
Naturally weight-friendly
Whole plant foods are low in calorie density and high in bulk, so a whole-food vegan pattern tends to reduce calorie intake without deliberate restriction. Vegans have the lowest average body weight of any diet group in the large cohorts, and randomized trials show modest weight loss when people switch.
Risks & who should be careful
B12 is a hard requirement, not a suggestion
Vitamin B12 comes from animal foods and fortification - an unfortified vegan diet supplies essentially none, and deficiency builds silently over months to years before it shows. Supplementation is the standard guidance for everyone eating this way; the form and dose are conversations for your clinician.
Protein and minerals need engineering
Iron and zinc from plants absorb less readily than from animal foods, and calcium and iodine lose their default sources when dairy leaves the plate. None of this is unmanageable, but it does not manage itself - this diet fails quietly at the micronutrient level when it fails.
On glucose or blood-pressure medication? Loop in your prescriber
A higher-carbohydrate pattern plus the weight loss that often follows the switch can move blood glucose and blood pressure enough to matter. If you take medication for either, tell your prescriber before you change how you eat - doses are theirs to adjust, not the diet’s.
Pregnancy, breastfeeding, and growing kids raise the stakes
Professional dietetics bodies consider a well-planned vegan diet workable at every life stage, but "well-planned" carries real weight here: B12, iron, iodine, choline, and omega-3s all become critical when someone else’s development depends on them. Work with a clinician or registered dietitian rather than winging it.
Kidney conditions, bone health, and restriction history
Kidney conditions that come with potassium or protein limits deserve professional guidance before a switch, since plant-heavy eating changes both. Older adults should keep deliberate attention on calcium, vitamin D, and protein - one large cohort reported higher fracture rates among vegans. And because this is a restriction-defined diet, anyone with a history of disordered eating should approach it with support.
The metabolic-health factor
The solid ground: a vegan diet reliably lowers LDL cholesterol - one of the most consistent diet effects in randomized trials - and is associated with lower cardiovascular risk, lower blood pressure, and less type 2 diabetes in the large cohorts that have followed vegans for decades. If your primary metabolic concern is lipids, this pattern has genuine evidence behind it.
What it is not: an automatic glucose diet. At 45–55% of calories from carbohydrate, your glycemic response rides almost entirely on carb quality. Intact legumes, whole grains, and vegetables arrive wrapped in fiber and digest slowly; refined flours, vegan desserts, and processed substitutes behave like the refined foods they are. Done on refined substitutes instead of whole plants, the metabolic advantage disappears - the label on the package does not change what the food does.
And it demands planning in a way most diets do not. B12 supplementation is mandatory, protein needs deliberate pairing - legumes with grains, nuts, or seeds - and several minerals need conscious sourcing. The pattern rewards people who treat it as a practice rather than a purchase.
Where the evidence thins: the long-term benefits rest on observational cohorts, and vegans in those cohorts differ from average in many health behaviors at once, so some of the advantage is the person rather than the plate. No large randomized trial has run a vegan diet out to hard outcomes like heart attacks, and honest reporting means saying so.
What recent research says
The randomized-trial evidence is strongest on blood lipids: trials comparing vegan diets against omnivorous control diets consistently find lower LDL cholesterol, with meta-analyses of trials also showing modest reductions in blood pressure and body weight. These are short- and medium-term trials measuring risk markers, not decades-long outcome studies - but the direction is consistent across them.
The long-term picture comes from observational cohorts. EPIC-Oxford in the UK and Adventist Health Study-2 in North America together follow more than 150,000 people, including large numbers of vegetarians and vegans, and both associate plant-exclusive eating with lower ischemic heart disease, lower hypertension, and lower type 2 diabetes prevalence. The standard caveat applies with full force: people who choose vegan diets differ in many ways that also protect health.
The cohorts also produced honest wrinkles. A long-term EPIC-Oxford follow-up reported around 2019 that vegetarians and vegans had lower ischemic heart disease but a modestly higher stroke rate than meat eaters - a finding that remains incompletely explained. Around 2020 the same cohort reported higher fracture rates among vegans, which is why calcium, vitamin D, and adequate protein get their own line in the risks above.
In adults with type 2 diabetes, small randomized trials of low-fat vegan diets have reported improvements in weight and glycemic measures compared with conventional diet advice. Worth noting: in those trials, medication changes were made by study clinicians as the numbers moved - the same rule that applies outside a trial.
The most useful recent development is the quality distinction. Cohort analyses that score plant-food quality - separating whole-plant patterns from refined ones - find the benefit concentrates heavily in the whole-plant version, and that a refined plant-based diet can associate with worse outcomes than a mixed diet. The research increasingly agrees with the practical advice: what matters is not just what you exclude, but what you build the plate from instead.
Evidence summaries, not medical advice - nutrition research moves, individual responses vary, and your clinician knows your history.
How metabomap tracks it
Choose vegan in metabomap and the macro calculator sets your targets to this pattern’s shape - 45–55% carbohydrate, 15–20% protein, 25–35% fat - plus a daily fiber target. For a vegan diet the fiber line is the honest scoreboard: it is the number that separates a whole-plant day from a refined-substitute day, and we put it in front of you daily.
Your food diary computes totals server-side as you log, net carbs included. The weekly meal planner draws only from vegan-compatible recipes - everything animal-derived is filtered out of the pool - so planning the week does not mean re-checking every ingredient list yourself.
The micronutrient report (Premium) shows what your food actually provides - iron, zinc, calcium, and the rest of the shortlist this diet asks you to watch - and it splits food from supplements, so B12 tells the truth twice: near zero from unfortified plants (that is the diet, not a logging error), and whatever your logged supplement stack adds back. Supplementation is standard guidance on a vegan diet; the report is where you check yours is doing its job.
Weight, blood pressure, and sleep log in seconds - by hand, or by free Fitbit sync for weight and sleep - so the outcomes this diet is supposed to move sit next to the food record that is supposed to move them. And if you keep a blood glucose meter, logging readings lets you watch carb quality show up in your own numbers - the fastest feedback loop there is on whether your vegan diet is the whole-plant kind.
Questions, answered
Do I really need a B12 supplement?
Yes. No unfortified plant food reliably supplies vitamin B12, and deficiency develops silently over months to years. Fortified foods can contribute, but supplementation is the standard guidance for everyone eating fully plant-exclusive - ask your clinician what form and dose fit you.
How do I get enough protein without animal foods?
Anchor every meal in legumes - lentils, beans, tofu, tempeh, edamame - and pair them with grains, nuts, or seeds across the day so the amino acids complement each other. Hitting 15–20% of calories as protein is very achievable this way; it just requires building meals around a protein source instead of assuming one shows up.
Is a vegan diet automatically healthy?
No - vegan describes what is excluded, not the quality of what is included. Fries, soda, and most packaged desserts are vegan, and a diet built on refined substitutes loses the metabolic advantages the research describes. The evidence behind this pattern belongs to the whole-plant version: legumes, whole grains, vegetables, fruits, nuts, and seeds.
Can I combine vegan with low-carb or keto?
It is possible but genuinely hard: removing animal foods and most carbohydrate at once narrows the plate to tofu, tempeh, nuts, seeds, avocados, and low-carb vegetables, and protein gets difficult to hit. The macro shape on this page is the moderate-carb version, which is where the vegan evidence base actually lives. If you attempt a stricter hybrid, track closely and consider professional guidance.