Published by Barbara of North, which also owns Fuels by Barbara and Greens of North.

Vegan But Still Tired

Vegan and Not Eating Enough: The Hidden Calorie Gap, the Signs and How to Fix It in a Week

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A bright plant-based kitchen: beautiful, and easy to under-eat in

This is general information about food and training, not medical advice. If you have a diagnosed condition or take medication, talk to your doctor before changing your diet or exercise.

Evidence file version gaps-fatigue-v1, as of October 8, 2026.

This is the gap that hides best, because it looks like success. The plate is enormous, green, photographed. The woman eating it is cold, tired, waking at four, losing hair, has not had a proper period in months, and has been told by everyone that she is doing everything right. She is eating 1,300 kilocalories a day and training five times a week. Plants are mostly water and fibre; a kilo of vegetables carries less energy than a handful of nuts. Unless a plant-based plate is built deliberately around dense foods, it under-feeds, and the body responds by turning down everything it can spare: temperature, hormones, mood, repair.

The signs you are not eating enough

In women who train, this pattern has a name, low energy availability, and it is defined by numbers, below.

The numbers

MeasureFigure
Typical energy need, woman 55 to 70 kg, moderately active1,800 to 2,200 kcal a day
With daily training2,200 to 2,600 kcal a day
Energy availability (intake minus training energy, per kg of fat-free mass)below 30 kcal per kg is low; 45 kcal per kg is healthy
What 1 kg of mixed vegetables carriesabout 250 to 400 kcal
What 100 g of mixed nuts carriesabout 600 kcal

Worked example: a 65 kg woman with 48 kg of fat-free mass who eats 1,500 kcal and burns 400 kcal in a run has an energy availability of (1,500 minus 400) divided by 48, which is 23 kcal per kg. Her body reads that as famine and behaves accordingly.

There is no blood test for this gap. The three-day weighed log, an honest count of training, and the arithmetic above are the test, and they are more reliable than any marker.

The foods that close the gap without a bigger plate

Density is the whole game. Add fat, add nuts and seeds, add the foods you were avoiding because they were “calorie-dense”, which is precisely the quality you need.

FoodPortionEnergyHow to use it
Mixed nuts40 g240 kcala handful mid-morning, every day
Tahini30 g180 kcalstirred into dressings, over roasted roots
Peanut or almond butter30 g180 kcalon the morning oats, on apple slices
Extra virgin olive oil1 tablespoon120 kcalover everything that is already cooked; three a day
Avocadohalf160 kcalon toast, in the bowl
Oats, dry80 g300 kcalporridge made with soy milk, not water
Dried fruit (dates, apricots, figs)50 g140 kcalin the oats, after training
Soy milk500 ml across the day230 kcalthe kettle-side habit
Tofu, firm200 g290 kcalthe dinner anchor
Hummus100 g250 kcalwith everything
Dark chocolate30 g170 kcalbecause joy is also a nutrient
Granola with nuts60 g280 kcalover plant yoghurt

Two tablespoons of olive oil, a handful of nuts, a spoon of tahini and soy milk in place of water in the porridge add about 700 kcal to a day without adding a single extra plate.

The rules

Eat breakfast within an hour of waking, and make it the densest meal: oats with soy milk, nut butter, seeds and fruit is 600 kcal that sets the day’s appetite straight.

Add fat to every cooked meal after it is cooked. Oil, tahini, nuts, avocado. This is the lever with the largest effect per effort.

Cap the fibre. Above about 50 g a day, fibre fills you before you have eaten enough; most under-fed vegans are at 60 to 70. Swap some raw vegetables for cooked, some beans for tofu, some wholegrain for white rice on training days.

Fuel the training. 30 to 60 g of carbohydrate in the hour before and a real meal within two hours after; a banana and a date before, the lentil bowl after.

Stop the “clean” rule. Energy from a flapjack is energy. A plate that must be perfect is a plate that is usually too small.

Watch the period, not the scale. A regular cycle is the clearest sign that a woman is eating enough; its absence is the clearest sign she is not. If it has been gone for three months, this is the gap to close first, and a clinician should know.

The one-week fix

  1. Log three days, weighed, and run the arithmetic above once. You will not need to do it again.
  2. Make porridge with soy milk and a spoon of nut butter every morning this week.
  3. Add a tablespoon of olive oil or tahini to lunch and dinner after cooking.
  4. Put a bag of mixed nuts in the bag you carry; eat a handful at eleven and at four.
  5. Keep training, but eat a date and a banana before and the lentil bowl after, every session.
  6. Expect warmth within days and sleep within two weeks. The period and the training progress follow over two to three months.

What the research says

Questions women ask

I am trying to lose weight. Does this apply to me? Yes, more than to anyone. A body in famine holds on to fat and sheds muscle; eating enough, with protein and strength work, is how the composition changes. A deficit of 300 to 500 kcal from a properly fed baseline works; a deficit from 1,300 does not.

How can I be eating too little when I am always eating? Grazing on vegetables, fruit and rice cakes is a lot of chewing for very little energy. Density, not volume, is the fix.

Will the extra fat make me gain weight? Adding 500 kcal to a day that was 1,300 brings you to a number your body stops fighting. Most women find the scale moves less than they feared and the energy, warmth and sleep move more than they hoped.

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