STUDIES show that immigrants gain weight and their children tend to live shorter lives than their parents. Their eating habits change for the worse the longer they stay.

But there is very little information on how many revert back to their cultural habits in difficult economic times Ñ and how many actually become healthier as a result.

A few years ago I interviewed Thien Tran, 47, who came from Vietnam and managed a beauty salon and nail spa on Nob Hill, and he said that he had been eating better and losing weight since the economic downturn.

“My wife makes Vietnamese food and I take it to work,” said Thien. “I used to order burgers and fries or Thai noodles, but that is too expensive. My lunch went from US$8 to US$2 a day.”

In lean times, Thien had returned to eating his traditional Vietnamese foods. “It’s either rice and fish, rice and salted pork, rice and steamed chicken, with lots of vegetable,” he rattled off his menu, laughing.

Mr Wang, 67, lived in a three-generational household in a crowded two bedroom apartment near the Tenderloin here in San Francisco. He came from Hong Kong where he worked for years in a restaurant as a chef.

He retired but his wife was out of a job when the recession hit in 2009. Now she works part time in a grocery store.

But Mr Wang has been most resourceful: he goes to Chinatown every day to find the freshest and cheapest bargain and cooks for his wife, son and daughter in law, and his three grandchildren. “For 7 people, we are eating very well for maybe US$35 dollars a day,” he said. “The trick is time and patience. And you have to have cooking experience.”

A regular meal at the Wangs: Steam chicken with ginger, fried tofu, fish in black bean sauce, stir-fried fry bok choy in garlic, fresh fruit.

It’s a cultural defense against an economic crisis that works for many who come from Asia and other parts of the world.

After all, it’s not just Thien’s waistline that’s shrinking Ñ his pocket book is too, as fewer customers are able to afford his services. “They come [for a dye job],” he noted with a sigh, “when the roots are really showing. And instead of three weeks, now it’s six weeks for nails.”

Fresh spring rolls

From beauty to shopping and eating out, American behaviors are changing radically. Macaroni and cheese boxes are selling swiftly, along with Spam, the canned luncheon meat invented during the Depression era.

From McDonalds’ value meals to Burger King’s two bite-sized burgers for US$1.39 to Starbucks’ US$3.95 coffee with an egg sandwich, cup of oatmeal or coffee cake, businesses are luring customers with low-priced, high-calorie menu items.

Over all, the trend is that people’s eating habits are worse off in down economic time.

“Mothers who work full-time reported fewer family meals, more frequent fast-food meals, less frequent encouragement of healthy eating, and lower fruit and vegetable intake,” according to Street Talk Live, a radio talk show. “Nutritional deficits in children could lead to some big and potentially life-long problems for children, who may have more health issues, behavioral problems and academic performance issues.”

But does frugality have to be synonymous with being unhealthy? “The answer is no,” said New York chef Irene Khin, who runs Saffron59, a catering business that specializes in Asian-fusion cuisine. “You can make a nutritious meal for less than a McDonalds’ lunch combo and feed three people,” she told me.

In fact, Khin often cooks lunch with her staff of four. “We made Chop Chae [Korean mixed vegetables with beef and noodles] enough for six. It costs around US$12.”

Andrea Nguyen, a cooking teacher and the author of the cookbooks such as “Into the Vietnamese Kitchen: Treasured Foodways, Modern Flavors,” and “Asian Tofu,” readily agreed.

“Being poor doesn’t translate to eating badly,” said Nguyen, who runs a website on Vietnamese cooking. A few years ago, she “saw on CNN where a reporter went shopping for US$6.42 a day as if he were on food stamps, and I thought I could eat lots of rice, vegetables, tofu and small, inexpensive fish on that amount of money.”

The reporter would do better, Nguyen noted, if he were to shop at “ethnic markets,” which she said are “great sources for fresh, reasonably priced ingredients.”

In addition to being cheap, traditional Asian foods can be very flavorful, she said. “Soy sauce, fish sauce, chili, ginger and lime would provide lots of flavor. Mung beans and soy products would lend protein.” It’s a matter of cooking your own food, according to Nguyen. “People can save a lot of money if they prepare more meals at home.”

Seafood curry

The perennial complaint is that home cooking takes time. But Khin quickly dismissed that idea. “I can make steamed rice and several dishes, and store it in the fridge for a week. You can eat well and healthy for very little if you’re willing to put effort into it.”

Khin suggested delicious recipes like curry fish and panthay noodle that take less than 20 minutes to make.

“When money is tight you can still eat well,” said Andrea Nguyen. “In fact, when my family came to the US from Vietnam, we made the most wonderful meals from inexpensive chicken backs that we simmered for stock and then removed the meat and skin for rice. I fondly remember the flavors of those Ôlean’ times Ñ though we were eating much richer foods then than we are today!”

But it’s not just a culinary habit for immigrants.

Chef Irene Khin, who came here as an immigrant from Myanmar, said the most important message for Americans to hear is that being frugal doesn’t have to mean being unhealthy. By “taking advantage of other cultures around you,” Khin said, “you can find good recipes and make something healthy for yourself and your family and save money. You don’t have to eat roast potato with steak all the time.”

Andrew Lam is an editor at New America Media and the author of “Perfume Dreams: Reflections on the Vietnamese Diaspora,” “East Eats West: Writing in Two Hemispheres,” and his latest, “Birds of Paradise Lost,” a collection of stories about Vietnamese refugees struggling to rebuild their lives on the West Coast.