Take out a blank sheet of paper,label it Page 218: The Chemistry of Food

What Happens During Digestion?

What Happens During Digestion?

There are over 300 different species of bacteria living in your gut, that

digest your food!

Chemical reactions!

What Is Food Made Of?• Carbohydrates

(various combinations of C, H, and O)

• Fats (long chains of C and H)

• Proteins (combinations of N, H, O, C, and others)

What Is Food Made Of?• Carbohydrates

(various combinations of C, H, and O)

• Fats (long chains of C and H)

• Proteins (combinations of N, H, O, C, and others)

What Are Calories?Calorie – a unit used to measure the amount of energy in food

Glucose:3.4 calories per gram

Sucrose:3.9 calories per gram

(1 Calorie = energy required to warm 1 liter of water by 1°C)

What Are Calories?• Average human needs about

2,000 Caloriesper day to run basic body systems

• Activity/exercise requires extra calories

• Excess calories eaten are stored as fat (1 lb. of fat = 3,500 Calories)

• Extra calories needed are taken from fat reserves

Why Do We Love High-Calorie Foods?

For most of human history, getting food was hard work. So humans evolved to

love the taste of high-calorie foods; we needed the energy!Today, we have the same

taste-buds, but much different lifestyles. As a result, we

overeat; almost 70% of adults are considered overweight.