In an environment where tiffin services are taken primarily by working professionals who after the age of 30 start showing serious lifestyle related health concerns, just counting calories doesn't impact health as much. It has been proven in studies that if the calorie count is the same, and "bad" calories are replaced by "good" calories, the impact on good health is substantial. Below the age of 30, counting calories at a desk job definitely helps as it keeps weight gain for a sedentary executive in check.
As for vegan diets, unless vegan diets are raw – more raw and fresh fruits and vegetables with nuts and seeds – they don't offer much benefit to the heart. This is because of mass cooking procedures in commercial kitchens that kill the nutrients in vegetables when overcooked or not covered and cooked. The addition of paneer (in some vegetarian non–vegan diets) and certain lentils are inflammatory for chronic pain related issues faced by many professionals who have back, wrist or knee issues. The trend is definitely encouraging because it eliminates the bad foods – meats, white flour, sugar, processing – found in fast foods that are the first option for younger employees. But this also eliminates the good proteins and anti inflammatory properties found in eggs and fish. Tiffin services should get high end: offer verticals of raw diets, or specialised meals for diabetics and heart patients, which some are already doing so. That has clear health benefits and is a sound business model too.
