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Lab 5
Food Calories and Land
If you check any popular newspaper, magazine, or television news show in the last year or two, you have
heard this same story countless times: Americans are fat, and getting fatter. Every year, new studies
reported that show that the situation is getting worse. By 2002, the National Center for Health Statistics
found that 65% of all adult Americans were overweight. This figure is significantly higher than the 47% of
adults who fell into this category just 20 years before in 1980. To make matters worse, 31% of adults
were more than 30 pounds overweight, moving them into the obese category. This is more than double
what it was in 1980, when only 15% of adults were considered obese.1
It is doubtful that this situation is going to change
anytime soon. In the same study, the NCHS
found that 16% of children aged 6-11 were
overweight. This is a fourfold increase over the
percentage in 1960, when only 4% were
overweight. 2 The interesting thing is that the
majority of this increase has occurred over the last
20 years, just as it has for adults. In 1980, only
7% of children were considered overweight.
What does this data mean? It means that we
should expect to see coronary disease increase,
as more people experience clogged arteries. It
also means that we should continue to see a rise
in many other types of diseases that are linked to
obesity, such as Type II diabetes. This, of course,
means that there will be a serious impact on the
economy, as there will be higher insurance rates
to cover medical bills and more loss-time on company payrolls as people fall ill. But, not so obviously, it
also means that there might be a serious impact on the environment. To understand why, let us look at
the average diet of Americans.
Fig. 1: U.S. adult obesity rats (Dept. of HHS)
One reason for the increased rates of obesity is an increasing lack of exercise. We lead a more
sedentary life today than we did 30 or 50 years ago. This is due to many factors, from suburbs designed
to reinforce transportation by car to our increased use of computers and television. But another reason
for our increase in obesity is that our diet has changed significantly over the same time period. It is not
just that we eat more, but that we eat different foods in a different manner. The different foods that we
eat are processed by our bodies differently, resulting in greater weight gain.
Fifty years ago, food consumption in the U.S. was at its lowest point for the century. At that time, the
average American was consuming about 2,000 calories a day. Less than twenty years later (1970), this
figure had increased modestly to about 2,200 calories per day, which is about the what the USDA
recommends as an average for the total population4. However, we have greatly expanded our
consumption passed this recommended point. The average American today consumes just under 2,700
calories per day. This is more than what is recommended healthy active males in their early 20’s, which
constitute the group with the highest caloric intake. When one considers that this figure also includes
children and inactive adults, it is easy to see why our obesity rate is what it is.
Looking at just calories, though, does not tell the whole story. During the same time span that our caloric
intake has increased, the types of foods that we have been eating has also changed. Over one third of
the increase in calories from 1970 to 2000 was accounted for by an increase in grain consumption. Most
of this was in the form of refined grain products, such as white bread and pastries. An equally large share
of the increase was due to added fats and oils, like that found in fried foods and white bread. Besides
these two categories, the remainder of the increase in calories was due mostly to added sugars (about
20% of the increase).
Together, these three things help to explain some of the increase in obesity. Refined grain products are
quickly broken down by the body, causing an almost immediate increase in blood glucose levels like that
of added sugars. If this extra sugar is not used immediately, it gets stored as fat. At the same time, the
spike in blood glucose levels is usually followed by an increase in insulin to handle the huge load. Once
the spike has been processed, blood glucose levels usually fall below their normal levels, causing
feelings of sluggishness and lethargy in the body. This leads to a lack of exercise, which exacerbates the
situation. The addition of the fats and oils on top of this just causes the system to go even further in the
direction of adding weight.
Fig 2: Meat Consumption, 1980-2010
These were not the only large changes in our diet.
In the 1950’s, the average American consumed 138
pounds of meat. The majority of this (107 pounds)
was in the form of red meat from cattle and pigs.
Since that time, we have increased our meat
consumption to 195 pounds per person. While our
red meat consumption only increased by 7 pounds
during that time, we added an additional 46 pounds
of poultry to our diet. Such a large increase should
have resulted in a large caloric increase. However,
concern about fat in our diet during this period led to
leaner animals and cuts of meat, which actually
resulted in a lowering of the amount of fat in our diet
from meat.
These increases in consumption have had more than just an impact on our waistlines; they have also had
an impact on the environment. The mere fact that more food is being consumed means that more
product has to be transported to market, resulting in higher fuel usage. More oil and natural gas are also
needed to create the artificial fertilizers used to grow the crops, and more energy is needed to plant, and
harvest the crops. Both plants and animals require water, which means that the increased foodstocks
correspond to increased water usage. And while there has been a “Green Revolution” over the past 50
years that has allowed for greater crop production on each acre of land, these increases in per capita
consumption have resulted in a net increase in the per capita land usage. This would mean that, even if
our population was not increasing, we would need more land to be converted to farmland as our caloric
consumption increases.
This increased land usage is especially true in the case of meat and animal product consumption. In
general, the amount of meat that can be raised on a piece of land is about one-tenth that of the amount of
plant matter that can be grown on the same land. Since meat is about twice as dense in calories as plant
material, this means that the number of calories per acre of land is about 5 times more for grain and
vegetables than for meat. On average, an acre of land can grow about 1,200 per day of meat or about
6,000 calories per day of grain and vegetables. These estimates correspond to conversion factors of
.00082 acres per calorie for meat and .00016 acres per calorie for grain and vegetables. Thus, just the
increase from 138 to 195 pounds of meat consumed per person per year in the U.S. means that about a
tenth of an acre of land more is required per person to meet our food consumption needs. Before we
even consider any other farmland increases, this corresponds to almost 30 million acres of land that must
be used for agriculture that could be used for other purposes or allowed to remain wild.
Of course, some people might point out that not all land is equal. There are pieces of land in the U.S. that
can support ranching quite well, and that are not environmentally damaged by its use. For instance,
some High Plains grasslands are ideally suited to bison (American buffalo) ranching. The bison do not
overgraze, the land remains as a grassland because of their grazing, other animals and plants would
benefit from this use. This neglects, of course, the fact that we consume mostly beef and very little bison
in this country. Contrary to popular images in movies, cattle spend very little of their time out on the open
range grazing on grass. In today’s industrial ranching reality, cattle put on most of their weight by
consuming silage (grain) while packed in dense feedlots. This type of ranching relies heavily on growing
corn and other grain to feed the cattle, and on the liberal use of antibiotics to stave off diseases that the
cattle get from living in such close quarters. This, too, has an environmental impact, as we now have
measurable dosages of antibiotics in our rivers and streams from the runoff from these feedlots.
Additional Reading
The following link provides information on food and nutrition from the U.S. Department of Agriculture. The
site is maintained through the Consumer Information Center in Pueblo, Colorado.
USDA
Topic: The Food Pyramid
Summary: Contains information about food and nutrition.
Link:http://www.pueblo.gsa.gov/cic_text/food/food-pyramid/main.htm
References
1 http://www.cdc.gov/nchs/products/pubs/pubd/hestats/obese/obse99.htm, October 12, 2004
2 http://www.cdc.gov/nchs/products/pubs/pubd/hestats/overwght99.htm, October 12, 2004
3 USDA Agricultural Factbook 2001-2002, Chapter 2, http://www.usda.gov/factbook/chapter2.htm
4 http://www.ers.usda.gov/publications/aer772/aer772d , October 13, 2004.
Activity
In this exercise, you will investigate how your own diet affects the agricultural demands of a country. You
will do this by monitoring your food and drink intake for 3 days, and recording it on the attached activity
sheet. At the end of this time, you will add up the number of calories consumed and find the average
amount for each day. Most of your packaged food should come with some type of caloric guidelines. If it
does not, a fairly complete listing of the calories of various foodstuffs can be found here.
As best you can, you need to categorize the calories as coming from either plants or animals. For some
things, this will be easy. A steak or a glass of milk clearly fall into the animal calories category, while a
bowl of rice or a side dish of beans fall into the plant calories category. But what about plate of spaghetti
with meat sauce? For this, you should try to separate the meat sauce into the amount of meat and the
amount of tomato and other vegetables and then decide of calories for both. If you are in doubt, put the
calories in the plant calories category. If you do this, you then need to realize that your land usage
estimate might be lower than it actually is.
After calculating your average caloric intake and estimating the amount of land that is needed to provide
your daily intake, answer the questions on the activity sheet.
http://www.pueblo.gsa.gov/cic_text/food/food-pyramid/main.htm
http://www.cdc.gov/nchs/products/pubs/pubd/hestats/obese/obse99.htm
http://www.cdc.gov/nchs/products/pubs/pubd/hestats/overwght99.htm
http://www.ers.usda.gov/publications/aer772/aer772d
calories
Activity Sheet Calories and Land
Name:
Day 1 Day 2 Day 3
Calories Calories Calories
Meal Item Plant Animal Item Plant Animal Item Plant Animal
Breakfast
Lunch
Dinner
Total xxxxxx xxxxxx xxxxxx
Average plant calories = _____ Average animal calories = _____ Average calories = _____
Land usage = Plant calories____ x .00016 acres/calorie + animal calories____x .00082 acres/calorie
= _____ acres
1) How does your average consumption of calories compare to the current American average of 2700
calories per day?
2) There are 290 million people in the U.S. If all of them ate like you did, how much land would be
required for farming?
3) China has 1.2 billion people. There is a total of 2.37 billion acres of land in China, of which only 710
million is of agricultural quality. If all of the Chinese had a diet like yours, how much land would be
needed? Is it realistic for them to eat this much?
- Introduction
Diet
Environment
Additional Reading
References
ESA21: Environmental Science Activities
Lab #5 Human Ecology
NAME________________________________________
Instructions
Download and read the “ ” file before completing this answer sheet for Lab #5. The ‘pdf’ is the lab. This MS Word ‘ ’ is the answer sheet. You are to fill in the answer sheet and submit it for grading under Assignments.
Lab Activity
– Diet and Agricultural Demands
As described on page 3 of lab ( ):
In this exercise, you will investigate how your own diet affects the agricultural demands of a country. You will do this by monitoring your food and drink intake for 3 days, and recording it on the attached activity sheet. At the end of this time, you will add up the number of calories consumed and find the average amount for each day. Most of your packaged food should come with some type of caloric guidelines. If it does not, a fairly complete listing of the calories of various foodstuffs can be found at
http://www.thecaloriecounter.com/
or another similar site.
As best you can, you need to categorize the calories as coming from either plants or animals. For some things, this will be easy. A steak or a glass of milk clearly fall into the animal calories category, while a bowl of rice or a side dish of beans fall into the plant calories category. But what about plate of spaghetti with meat sauce? For this, you should try to separate the meat sauce into the amount of meat and the amount of tomato and other vegetables and then decide of calories for both. If you are in doubt, put the calories in the plant calories category. If you do this, you then need to realize that your land usage estimate might be lower than it actually is. After calculating your average caloric intake and estimating the amount of land that is needed to provide your daily intake, answer the questions on the activity sheet.
Once you are finished filling in the table (available on page 3 of this document below), answer the questions that follow.
All of page 3 and 4 will be graded, including the table and remaining 4 questions at the end.
Results
|
Day 1 – Calories |
Day 2 – Calories |
Day 3 – Calories |
|
| Meal |
Item Plant Animal |
||
|
Breakfast |
|||
|
Lunch |
|||
|
Dinner |
|||
|
Snacks & |
|||
|
Drinks |
|||
|
Total |
Average plant calories [(Day 1 + Day 2 + Day 3)/ 3] =
___________
Average animal calories [(Day 1 + Day 2 + Day 3)/ 3] =
___________
Average calories (Avg plant + Avg Animal) =
___________
Land usage = Avg. Plant Calories_________ x .00016 acres/calorie + Avg. Animal Calories _________x .00082 acres/calorie = ___________ acres
Questions
1) How does your average consumption of calories compare to the current American average of 2700 calories per day?
2) There are 314 million people in the U.S. If all of them ate like you did, how much land would be required for farming? Given the average American’s caloric intake, which translates to 1.03 acres per person, how much land is required to meet America’s food consumption?
3) China has 1.2 billion people. There is a total of 2.37 billion acres of land in China, of which only 710 million is of agricultural quality. If all of the Chinese had a diet like yours, how much land would be needed? If all the Chinese had the diet of the average American how much land would be needed? Is it realistic for them to eat this much, given their land limitations?
4) Why does it take so much more land to raise a calorie of animal-based food than plant-based food? (Think back to the first lab). In light of this discrepancy, do you think we face a food production problem or a food consumption problem?
