Food needs: How much is enough?

Experts revise energy requirements for the first time in 20 years


Energy recommendations help countries design school feeding programmes. These children in Honduras are getting ready to learn -- by eating lunch. (FAO/22082/G. Bizzarri)

When countries design school-feeding programmes or calculate food import requirements, they base their decisions on standardized estimates of how many calories people need to lead active and healthy lives. Recently experts invited by FAO, the World Health Organization and the United Nations University met at FAO headquarters for the Expert Consultation on Energy in Human Nutrition. Their aim was to assess those estimates, revise figures for certain groups and discuss a new concern in the developing world: obesity.

"There's been a long lag since the last consultation," says Eileen Kennedy, former Deputy Under-Secretary for Research, Education and Economics for the US Department of Agriculture and chair of the consultation. "The good news is that today we have better and more precise information." The recommendations from the consultation will be released in a report later this year.

The last time the experts held such a consultation was in 1981. Since then, a number of new tools and new data have enabled nutritionists to more accurately understand human energy requirements. At the same time, profound changes in lifestyle are leading to new health challenges.

Obesity along with hunger
One of the most significant changes is the emergence of obesity in countries still struggling to end hunger. A combination of increased income and the availability of more food, but not necessarily better food, is behind this change. So too is the fact that activity levels are decreasing in much of the developing world. In many cases, obesity occurs in the same household as hunger. (For more information on obesity, see the FAO in-depth Focus "The developing world's new burden.")

The rise in obesity also questions some basic assumptions about energy recommendations. For example the report from the last consultation had recommended providing additional food to undernourished children to allow them to catch up to normal weight. But at this consultation, experts from a number of developing countries pointed out a problem with this approach. "When the information was used to plan feeding programmes, it actually led to obesity in some cases," says Prakash Shetty, Chief of FAO's Nutrition Planning, Assessment and Evaluation Service.


Increased mechanization means people in the developing world are becoming less active. A tractor helps plough a field in Zambia. (FAO/11165/P. Johnson)

Being active, being fit
Experts at the consultation agreed that obesity needs urgent attention. Part of the solution is promoting physical activity since activity confers important health benefits while also burning calories. Everyone profits from increased activity, not just people who are overweight. "You need to eat every day and you need to be active every day," says Dr. Kennedy.

A number of assumptions about lifestyle were also challenged at the consultation. It turns out that people in the developing world are becoming less active than they used to be. Increased automation in agriculture means farmers expend less energy to get the same work done. And as incomes rise, people are adopting a more sedentary lifestyle, for example travelling by motorized vehicle rather than by foot.

New methods bring new understanding
Participants confirmed the validity of most of the previous energy recommendations--which was reassuring after years of criticisms that the figures might be too high. But better data using new tools led them to revise energy requirements for certain groups. (For more information on new tools, click here.) For instance, scientists discovered that children are less active than previously thought and as result, need fewer calories. By contrast, adolescents need more calories.

Revised recommendations are expected for certain groups. This woman in Thailand needs enough energy to feed herself and her baby. (WHO photo)

Specific recommendations for pregnant and breast-feeding women will also be revised. Energy requirements may decline in some cases since it turns out pregnant women are less active than previously thought. But instead of giving a single recommendation for how much weight gain leads to a healthy birth, a calculation will be made considering whether the mother is underweight or overweight.

And whereas the previous recommendations lumped everyone over 60 years of age in one group, the new guidelines will have sub-groups. "There's a big difference in energy needs and expenditures for individuals between 60 and 75 years old and those who are 75 and over," points out Irwin Rosenberg, Professor of Physiology, Medicine and Nutrition at Tufts University School of Medicine. People in their 60s and 70s may still be very active members of the household. But with increasing age people tend to exercise less while the body loses muscle mass -- thus requiring fewer calories overall. Both factors are more pronounced in those over 75.

The new report will reflect all these changes.

Turning science into policy
While the physiologists on the expert panel weighed in on scientific recommendations, the nutritionists must still turn the findings into practice. "We need to convene another consultation to make sure this is information developing countries can use," says Barbara Burlingame Senior Officer in FAO's Nutrition Impact Assessment and Evaluation Group. A consultation to address practical applications will be scheduled sometime after the new guidelines are completed.

One puzzle still to be solved has to do with the levels of activity that will be the basis for the new energy recommendations. The experts agreed on the importance of using an activity level consistent with good health. Unfortunately, the amount of physical activity discussed was higher than most people currently practice -- just at a time when people are becoming less active. If revised calculations translate into higher calorie levels without a concurrent increase in activity, the result could be more obesity, which is just what the developing world doesn't need.

"It's our job to make sure that doesn't happen," says Dr. Shetty.

Related article: New tools produce better results

17 january 2002

Related links

 FAO Home page 

 Search our site 

Comments?: [email protected]

©FAO, 2002