Short answer: not on most vegetables people picture when they hear the word. Lettuce, tomatoes, courgettes and most salad crops are genuinely low in calories per kilogram -- surviving on them alone would mean eating an unmanageable volume of food every single day. The word "vegetables" is doing a lot of hiding here, because calorie staples like potatoes, grains and dried beans are technically vegetables too, and they behave completely differently from a head of lettuce.
Not All Vegetables Are Created Equal
"Vegetables" is a loose category that hides an enormous range in calorie density. A kilogram of lettuce might provide well under 150 kcal; a kilogram of potatoes provides several times that. This is exactly why this site's own crop guides split vegetables into calorie staples and everything else -- because treating them the same way when planning a diet leads to a serious shortfall.
The honest version of "can you survive on vegetables alone" is really two different questions. Can you survive on salad-type vegetables alone? No -- the volume required would be genuinely impractical, even before accounting for the labour to grow and prepare that much food. Can you survive on a plant-based diet that leans heavily on calorie-dense staples like potatoes, grains and dried beans, supplemented by a range of other vegetables for nutrition? Yes, that's a workable plan, and it's exactly the kind of diet this site's calculator is built around.
One honest caveat: this calculator covers calories, not a fully complete nutritional profile. A plant-based plan can be nutritionally sound with the right variety and planning, but it's worth actively thinking about nutrients that are harder to source without any animal products, rather than assuming enough volume automatically covers everything.
Frequently Asked Questions
Can you survive on vegetables alone?
Not comfortably, and not on most common vegetables -- crops like lettuce, tomatoes and courgettes are low in calories per kilogram, so surviving on them alone would require eating an impractically large volume every day. A genuinely calorie-sufficient plant-based diet needs to lean on calorie-dense staples like potatoes, grains and dried beans, which behave more like the backbone of a diet than a typical salad vegetable does.
What's the difference between a calorie staple and a nutrition vegetable?
A calorie staple -- potatoes, grains, dried beans -- provides a large, reliable amount of energy per kilogram and per square metre grown, while a nutrition vegetable -- lettuce, tomatoes, peppers -- provides comparatively few calories but contributes vitamins, minerals and flavour; a workable diet needs both, but only staples can actually cover a household's core energy needs.
Is a vegetable-only diet nutritionally complete even if the calories work out?
Not necessarily -- a well-planned plant-based diet with enough variety can cover most nutritional needs, but this calculator specifically covers calories rather than a nutritionally complete diet, so growers relying entirely on plants should also plan deliberately for nutrients that are harder to get without any animal products, rather than assuming volume alone solves it.