Its co-authors, Tokyo-born Naomi Moriyama and her American husband, William Doyle, say families everywhere can learn from the Japanese way of doing things. The secret, they argue, is to "tweak" our own habits to bring them into line with the Japanese way of life.
"We got interested in this when the Lancet study came out and, of course, because of my background," says Moriyama, who grew up on her family's farm in rural Japan and now lives with her television-producer husband in Manhattan's Upper East Side with their son Brendan, 8.
"When I had a child of my own, I wanted to help my son enjoy healthy eating patterns and I needed a book like this," she says.
Delving deeper into Japan's health-giving secrets, the couple travelled widely in the country with their son, looking for answers in homes, schools, research institutions, supermarkets and farmers' markets.
They interviewed some of the world's leading experts on child health and nutrition, as well as a cross-section of Japanese mothers of young children living in New York.
Moriyama and Doyle concluded there were many probable reasons why the Japanese enjoyed good health, including regular comprehensive health check-ups, a cultural stress on hygiene, and sharp reductions in infectious diseases and infant mortality in the past 30 years.
But they also found that the traditional Japanese lifestyle was in line with today's advice on staying healthy, with its emphasis on eating more fruit and vegetables and less fat, meat, dairy and sugar, as well as taking regular physical exercise.
Japan has the lowest prevalence of childhood obesity in the world.
So what are Japanese families doing right - and what, if anything, can parents learn from them?
Moriyama and Doyle's advice is to give family food habits a "Japanese-style tweak", with more emphasis on nutrient-dense vegetables and less on meat, fat, dairy and sugar. A typical Japanese meal, they point out, will be vegetable-based; flavoured with strips of fish, chicken or beef, it might also contain water chestnuts, mange-tout, mung sprouts, pak choi, mustard greens, rice and herbs.
Vegetables are packed with nutrients and, being "water rich", they have "filling power", protecting against overeating and obesity.
In particular, they advise, rice is far lower in calorie density than, say, bread or pasta, leaving less room for kids to crave junk foods. "Rice is the bedrock of East Asian cooking," says Doyle. "Once cooked, its high water content gives a feeling of fullness."
It's not just the type of food but the style of eating that appears to promote good health. The ancient Japanese saying: "He who has his stomach full only 80 per cent will not need a doctor" sums up the sense of moderation.
"The style of eating means they feel full and energised," says Doyle.
Yet as the book makes clear, Japan is a nation in love with healthy, delicious food. Moriyama recounts how her mother, Chizuko - a "kitchen goddess" - taught her a lifelong pattern of "food joy". Children are taught, both at school and at home, how food is grown, prepared and ritually eaten, usually with the family, all of which makes for healthy eating patterns.
Sweet treats, chips and ice cream are not demonised, she says, but with smaller kitchens and less storage space, neither are they kept in large quantities at home.
The way food is served is also key: each person is given a small bowl, and several dishes - vegetables, rice, miso, fish or meat - are served communally, also in moderately sized bowls. Moriyama points out that this makes it easier for children to sample a variety of food. "Our tradition of communal eating encourages a healthy, relaxed attitude; it's not a question of a child having to finish everything they are given."
Also, the school-lunch programme - originally intended to feed hungry children in the wake of Japan's post-war economic devastation - hasn't changed much in the past 40 years. Healthy dishes are based on locally produced ingredients; there are no vending machines.
There is another basic principle keeping millions of Japanese children healthy: walking to school and back, at all ages. "It means that the recommendation that children engage in at least 60 minutes of moderate to intense exercise is built into their daily lives," says Doyle.
Japanese society is not perfect: smoking is still common (although discouraged), as is excessive drinking, and a high salt intake is associated with stroke and stomach cancer.
Japan's suicide rate is also comparatively high, because of financial problems and isolation among a growing elderly population.
Fastfood outlets such as McDonald's and KFC are booming, resulting in increases in BMI and cholesterol. All of which means much needs to be done if Japanese children are to keep pole position. Moriyama admits their son loves Western-style food, too.
"Living in New York, he is exposed to pizza, pasta, hamburgers and fries - and I do make all of that, though I try to use healthier ingredients," she says. "Just yesterday I picked him up from school and gave him a cookie. But as well as chocolate chips, it contained chia seeds, banana, grated apple and even leafy green veg."Telegraph Group Ltd
