Good evening. It is 11.45 pm on a Saturday
night here in New York City, and we are going to make an experiment. We are going to walk
for 15 minutes, and we are going to try to count how many eating opportunities we encounter.
We’ll start from Times Square then wander a little bit randomly, crosstown, then down
along Eight Avenue and then cross again and up until we are back to where we started.
And let’s see how it goes. The Centers for Disease Control and Prevention
of the United States Department of Health, annually updates a shocking presentation called
the history of state obesity prevalence. Starting from 1985, it shows a map of the US with the
number of obese individuals by state as a percentage of the entire population. As you
can see, for 1985 we have no data for most states, the light blue states had a rate of
obesity of less than 10%, the darker blue states between 10 and 15%. As we move forward
in time data become more complete, but by 1990 you can see a few states becoming dark
blue, because the rate of obesity went up in the 15 to 20% range. Dark blue spreads,
and in 1997, some yellow appears, and those are the states with more than 20% of obese
individuals. More yellow, and then some orange. More than 25% of obese. Orange spreads, and
then, whoops, some dark red, more than 30% of the population is obese. Red spreads, and
here we are in 2010, with every state above the 20% cutoff, many of them above 25%, and
a scary number above 30%. What’s so scary about this is not just the present rates of
obesity, but the trend. In less than 30 years, the rates of obesity have almost tripled.
Clearly, we have been doing something wrong. And clearly we have a big problem here.
In 1997 the world health organization formally recognized obesity as a global epidemic, or
pandemic. In the US, more than 1/3 of adults are obese, but if we include those that are
overweight, we are talking about more than 2/3 of the population, and what’s even more
troubling, the prevalence of excess body fat among infants and children is increasing dramatically.
Overweight and obesity are without any doubt the most common nutritional disorders in the
U.S and around the world as well. It is estimated that 40 to 60% of the population of all industrialized
countries is either overweight or obese. The world health organization defines overweight
and obesity as conditions characterized by excessive fat accumulation that presents a
risk to health. This definition is very appropriate because it focuses on two important points:
first, the problem is fat accumulation, and not weight per se. It is common for overweight
people to say that they want to lose weight, but in fact what they want to lose is fat,
not lean mass, not bones, or water, or muscles. Second, these conditions present a risk to
health. Although many times we think of overweight and obesity as merely a problem of how we
look, these conditions present very serious dangers for our health and dramatically increase
the risk for a plethora of life-threatening diseases, including liver disease, cardiovascular
disease, type II diabetes and some types of cancer. Another invalidating consequence of
obesity is osteoarthritis, because of all the extra stress on the joints, in particular
hips, lower back and knees that have to carry all that excess weight. With the increased levels of food security
and food availability that characterized some areas of the world after the industrial revolution,
and to an even greater extent after world war two, it soon became evident that non only
food deficiencies, but also food excesses pose great dangers to our health. As we have
seen, overweight and obesity began to spread dramatically, and the relationship between
over-eating and chronic disease became more and more clear.
To make things worse, our genetic makeup is still largely that of a caveman, and so we
are programmed to accumulate. Our genes are not very well adapted to deal with the excess
of eating opportunities that we experience today. Our body is much better at protecting
itself from deficiencies, than it is at protecting itself from overabundance.
It is evident that the goal of nutrition is not only to meet the minimum intake levels
of energy and nutrients in order to prevent deficiencies. There has to be an upper limit
as well. We need to prevent deficiencies, but at the same time also avoid excesses.
As we will learn in this course, overweight and obesity are complex problems and there
are many factors contributing to them, but certainly the way we eat, how much we eat
and how much we move play a key role. In parallel with increased food availability
and consumption, there are a couple of other trends that have contributed to the obesity
pandemic. Our lifestyle have changed dramatically in just a couple of generations, and we are
much more sedentary today than we were less than a century ago. Not only do we eat more
food in absolute terms, but we eat more energy dense food, that packs a lot of calories per
bite. We eat more empty calories, food that provides energy but it is not very nutritious.
In the 19th century, new technologies available to the food industry made it possible to refine
grains to make white flour, and to make white sugar from sugar cane and sugar beet. Eating
‘white bread’ and ‘white sugar’ soon became the norm, and these products were marketed
as cleaner, safer and more nutritious. Alas! Such “refined” foods would soon become
the serial-killers of the 21st century, bringing with them rampant problems of nutrient deficiencies,
obesity, diabetes and cardiovascular disease. Like we already said many times, the major
diet-related risks today are largely different than what they were in the past, at least
in our rich, post-industrialized countries. When we walk down the street, we don’t see
very many people with bleeding gums and falling teeth due to clinical nutrient deficiencies.
But we see a lot of people who are overweight and obese, and we know that this carries equally
serious dangers. This is what’s killing us today, and it is strongly linked to diet
and lifestyle: poor dietary choices, and excess food consumption.
Food availability stimulates food consumption, and the fact that during our fifteen minutes
walk in midtown manhattan we have been exposed to fifty-two opportunities to get food just
a step away from us, certainly doesn’t help.