Food needs: How much is enough?
Experts revise energy requirements for the first time in 20 years
"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
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.
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
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
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