She waited outside her home for the monk, who arrived for the offering at his regular time, chanting a short blessing before leaving for the next house. As his alms bowl was filled with bags of food and packaged drinks, he transferred its contents to a bucket carried by an assistant. Within 10 minutes, the bucket was filled to the brim with culinary offerings.

“I don’t really know about obesity in monks,” Ms. Vilawan said. “But I do realize that the monk who comes at 6 o’clock is pretty heavy, and his health seems to have deteriorated lately.”

Working with the Thai government and religious authorities, Professor Jongjit manages the Healthy Monk-Healthy Nutrition Project. Funded by the Thai Health Promotion Foundation, an autonomous government agency, its goal is to improve monks’ lifestyles through education about nutrition and physical fitness.

Its pilot program in 2016 involved 82 monks at temples and a monastic college, and its results were positive, with weight loss and lowered cholesterol levels recorded.

Now the project publishes recipe booklets that Buddhist devotees can use to make healthy and inexpensive meals for monks. Some suggestions include brown rice with a small amount of protein and lots of vegetables. (While traditional Thai food mixes a little meat or fish with plentiful vegetables, modern cuisine uses much more fat and sugar.)

The project encourages monks to keep a log of their daily physical activities. Exercise, something as simple as walking around the temple for at least 40 minutes a day, can make up for the quiet pace of their monastic duties.