A full pan of stir fried vegetables: kale, purple cabbage, broccoli, carrots, and snow peas. This is the class of plate the trial's vegan group ate more of, high in water and fiber relative to its calories.
Margaret Barse (Alabama Cooperative Extension System)
Illustrative. Not a photograph from the trial itself, which did not publish photographs of participants' meals. It is here because it shows the kind of high volume, low energy density plate the vegan group's diet was built from.
A Low Fat Vegan Diet Cut About 357 Calories A Day Without Anyone Eating Less Food
Every time I write about eating more plants, I hear the same worry back: I will just end up hungry. A new analysis of a 16 week randomized trial gives that worry an actual number, and the number is not about willpower at all.
- In a 16 week randomized trial, adults with overweight who ate an all you can eat low fat vegan diet took in about 357 fewer calories a day, while eating roughly the same weight of food as before.
- The lever was energy density, calories per gram of food. The vegan group's energy density fell about 30 percent. The control group's barely moved.
- Bigger drops in energy density predicted more weight loss even after accounting for total calories, meaning the shift did more than plain arithmetic explains.
- It is a secondary analysis of one existing trial, run by a vegan advocacy nonprofit with an unblinded, do nothing control group, so the mechanism is solid but the exact 357 calorie figure needs independent replication.
- 16
- Weeks, randomized trial
- 30%
- Drop in energy density for the vegan group. The control group's barely moved
- 357
- Fewer calories eaten per day, vegan group versus control
- 0
- Portion or calorie targets given. Nobody was told to eat less food
What the researchers actually measured
Researchers led by Hana Kahleova at the Physicians Committee for Responsible Medicine reanalyzed a 16 week randomized trial in adults with overweight. One group ate an all you can eat low fat vegan diet. The other group, the control, just kept eating the way they normally did. Nobody in either group was given a calorie target or told to shrink their portions.
What changed was the food itself. Plant foods carry more water and fiber per gram than meat, dairy, and eggs, so a plate that looks and feels just as full delivers fewer calories. The researchers call this energy density, calories per gram of food. Over 16 weeks, the vegan group's energy density fell by about 30 percent. The control group's barely moved. Food weight consumed did not differ meaningfully between the two groups, but calorie intake in the vegan group dropped by roughly 357 calories a day more than in the control group. The study was published in JAMA Network Open in August 2026.
Why calories per gram matters more than you would think
The part I found most interesting is not the average effect, it is what happened across individuals. Bigger drops in energy density predicted greater weight loss even after the researchers accounted for how many calories people ate. That suggests the volume of food landing on the plate is doing something beyond simple math, something related to fullness signals that respond to how much space food takes up, not just how many calories it carries.
This is also why the lesson generalizes past veganism. You do not have to adopt any particular diet label to use energy density. Swapping some calorie dense foods for high water, high fiber ones on any eating pattern should move the same lever.
Honest caveat
This is a secondary analysis of an existing trial, not a new one, and the same group of adults with overweight has generated several published analyses over the years, so the finding is new but the data behind it are not. The authors are also an interested party. The Physicians Committee for Responsible Medicine is a vegan advocacy nonprofit, which does not make the result false, but does mean it needs independent replication before the 357 calorie figure should be treated as settled. The control group simply continued eating as usual, with no attention matched comparison and no blinding, which dietary trials structurally struggle to achieve anyway. The underlying mechanism, that low energy density foods let you eat more volume for fewer calories, is well established outside this trial. The exact size of the effect in this one is the part that still needs outside confirmation.
What this means for you
You do not need to go vegan to use this. Energy density is just calories per gram, and you can estimate it by eye. Watery, fibrous foods like vegetables, fruit, legumes, and broth based soups sit at the low end. Oils, fried foods, and refined snacks sit at the high end. A practical way to use the finding is to build meals around foods with real volume and water content first, then add the calorie dense parts of a meal in smaller amounts, rather than trying to eat a smaller portion of everything.
I want to be clear about what this study does and does not show. It shows an association between a shift toward low energy density eating and reduced calorie intake, in one 16 week trial, in adults with overweight. It does not show that any single food swap will replicate the exact 357 calorie figure for you, and it is not a controlled feeding study where every calorie was measured. Treat the direction as solid and the specific number as a data point, not a guarantee.
Treat the direction as solid and the specific number as a data point, not a guarantee.
Primary sources
- Kahleova H, Znayenko Miller T, Maracine C, Holubkov R, Barnard ND. Vegan Diets and Dietary Energy Density. JAMA Network Open 2026; 9(8): e2627483. Read the paper
- Physicians Committee for Responsible Medicine, release via ScienceDaily, August 17, 2026. sciencedaily.com
Common questions
Do I have to go vegan to use this?
No. Energy density is a property of food, not of a diet label. You can lower the energy density of any eating pattern by shifting toward vegetables, fruit, legumes, and broth based foods and away from oils, fried foods, and refined snacks, whether or not you eat any animal products at all.
Does this mean the vegan group burned more calories?
No, and this is worth being precise about. The 357 calorie figure is a reduction in how much people ate, not an increase in how many calories they burned. It came from one arm of one trial, and it describes intake, not expenditure.
Is the 357 calorie number proven?
The underlying mechanism, that low energy density foods let you eat a full plate for fewer calories, is well established outside this trial. The exact 357 calorie figure comes from a single secondary analysis run by a vegan advocacy nonprofit, with no blinded or attention matched control group, so it needs independent replication before that specific number should be treated as settled.
Stay Curious.
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