Weighty Issues

a.k.a: Sadie's Independent Assignment

Weighty Issues

Basics

Our bodies were beautifully

created to survive.

Our bodies need fat.

Skinny does not mean healthy.

Exercise and healthy eating are the ONLY ways

to become healthy.

These are FACTS that society chooses to ignore.

The next two terms you will be introduced to play a great role in how your body handles food:

BMR

or Basic Metabolic Rate.

BMI

or Body Mass Index.

I will explain:

Calories

Calories is the unit used to express energy. In weight loss/gain terms, they express the amount of energy in foods that our bodies absorb when we eat. Different foods have a different calorie count. For example, 1 cup of lettuce has a lot less calories than 1 cup of ice cream. This is because of the food nutritional components: the amount of fat, carbohydrates, sugar, etc.

We can observe this in these next slides, which are pictures of different foods at 100 calories.

Our bodies need calories to function.

This is where our BMR

comes in to play.

Different bodies need different amounts of

calories. Someone who has a job sitting at a

desk all day and who watches television in their spare time, will most likely need less calories than someone

with a physically hard job who exercises daily. Not only does exercise require more energy, but muscle burns more calories than fat, even just sitting down on a chair.

Your BMR expresses the number of calories your body needs at a minimum.

So it's as if you counted the calories you burnt while doing nothing but lie in bed all day. It's the number of calories your body must burn just to keep itself running.

Several factors

affect your BMR,

such as age, muscle

mass, exercise, stress,

environmental temperature,

fasting/starvation,

hormones/genetics,

gender, etc.

To calculate your BMR, fill in these following equations

according to your gender.

Women: BMR = 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) - ( 4.7 x age in years )

Men: BMR = 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) - ( 6.8 x age in year )

To take exercise into account,

there is the Harris Benedict

equation:

Harris Benedict Formula

To determine your total daily calorie needs, multiply your BMR by the appropriate

activity factor, as follows:

•If you are sedentary (little or no exercise) : BMR x 1.2

•If you are lightly active (light exercise/sports 1-3 days/week) : BMR x 1.375

•If you are moderatetely active (moderate exercise/sports 3-5 days/week) :BMR x 1.55

•If you are very active (hard exercise/sports 6-7 days a week) : BMR x 1.725

•If you are extra active (very hard exercise/sports & physical job or 2x training) : BMR x 1.9

1 pound of fat=

3500 calories.

That means to loose 1 pound

one must burn 3500 net calories.

To calculate amount of net calories:

BMR+calories burnt doing exercise-calories consumed=Net Calories.

Therefore:

If Net Calories are less than 0. you will loose weight.

If Net Calories are equal to 0, you will maintain weight.

If Net Calories are greater than 0, you will gain weight.

This is where our BMI will come in.

Your BMI allows you to calculate your HEALTHINESS in body fat terms.

BMI = ( Weight in Pounds / ( Height in inches x Height in inches ) ) x 703

This formula will give you number between 20-30, depending on your body type. When you have calculated your BMI#, compare it to this table:

Health Assessment: BMI:

underweight: 18.5>

healthy: 18.5-24.9

overweight: 25-30

Obese: 30<

As with many formulas, there are many factors, such as lean body mass and genetics that are not taken into consideration. Therefore, do not entirely depend your health analysis on these equations.

For example, body builder Arnold

Schwarzenegger was 6ft and 250 pounds.

His BMI, from the formula, would be

equal to 33.5, which is classified as

obese. I think we can all agree Arnold

was far from overweight. Body fat

represented 8% of his total weight.

It is precisely these two terms I will be looking at: BMI and BMR and their factors.

I am most interested in observing the affects of age and gender on our BMI and BMR. I have made several graphs to represent my findings.

I researched the height and weights of men and women by age. (http://www.halls.md/chart/height-weight.htm) However, there were different percentiles to choose from, therefore I chose the median which is close to the average but not quite, so my numbers may not be 100% accurate.I have my two formulas for BMI and BMR, so I could just plug them in to draw my graphs: BMR vs Age, by gender and BMI vs Age, by gender.

As you may have guessed, I decided to attempt finding the rule for several of the graphs. BMR vs Age for women is defined by this rule: -27.6sqrt(x-20)+1441. Observe next slide.

While the BMR for Men...

Is defined by this rule:

Now compare the two genders.

I have observed that men's BMR is higher than women's. This is because men have more muscle mass, there for need more calories. Both men and women's BMR decreased with age, however, men's increased until the age of 40 before decreasing.

I also compared BMR to weight. As the persons weight increased so did their BMR. This is because as their body gets bigger, more calories are needed to keep it functioning.

For this graph I had to choose sample people from my information:

I chose a 35 year old man, therefore 68.5 inches and a 35 year old woman, therefore 64.7 inches.

BMR vs. Weight can be defined by a linear function: 13.7x+170.5 for men and 4.35x+804.5 for women.

Now to BMI.

Since BMI is only affected by weight and height in the formula, and it is the same for both men and women, it was harder to recreate the factors on a graph. But here you go:

This is one graph badly affected by the median samples I took. In real life, women's BMI is higher than men's because of lower muslce mass and child bearing.

However, we can observe that male BMI increases at about the same rate as womens, just starts off at a higher value.

Since the previous graph was not as accurate as I would have liked, I graphed out the BMI index, which is weight vs height. This gives us a good look at how height and weight affect our BMI. It is the same for both men and women.

To calculate the values for this graph, I used the BMI formula and did some algebra. I replaced the BMI with a BMI value and left weight as variable "w".

This project taught me a lot, not only about our body's way of working but also about functions in the real world, and how nature never seems to like to stick with the rules. Thank you for watching!

Keep these next statements in mind throughout

this presentation. They are not so much math related

but as my projects broaches a touchy subject, getting these ignored facts straight is the least I can do.

Yogurt:

80g

Peanut Butter:

15g

Cheese:

30g

Chocolate Chips:

20g

Cashews:

30g

Crackers:

40g

1 apple:

160g

Using this formula:

Women

Here are the...

Men

Body image and weight issues: a "math-y" psychology.