chowing down: do rats eat less when they eat slower? elise boos prashant patel margaret strom...

Chowing Down:Do Rats Eat Less

WhenThey Eat Slower?

Elise Boos

Prashant Patel

Margaret StromBiology 104 Section B

Slow Down!You’ll get full quicker and you won’t eat as much!

General Overview

• Eating Slower Reduces Food Intake– Behavioral Weight Management (Stuart, 1967)

• 60% of Americans are Overweight or Obese– Serious Health Consequences

• Satiety – the condition of being full– Rats – good models for research

Satiety Signals Terminate the Meal

Satiety Mechanisms

Hypothesis

If the rate of consumption is slowed down, the total amount of food intake will be lower.

Since satiety may be affected by the type of food consumed, we tested two foods.

Eating Speed = Food Intake

Macronutrient Content

3%

88%

3%6%

Fruit Rings

Fat CarbohydrateProtein Other

50%

18%

25%

7%

Peanuts

Fat CarbohydrateProtein Other

Energy Density – 3.75 kcal/g Energy Density – 6.07 kcal/g

Subjects

• Naïve male Sprague-Dawley Rats• Individually Housed• 12:12 Light/Dark Cycle• n = 9 for Fruit Rings study• n = 14 for Peanuts study

• Rat Chow and Water, except once per week• 24 hour food deprivation before trial• Tested 2 hours into light period

Materials & Methods

Phase IUnrestricted Trials

Establish Baseline Eating Speed

Phase IIRestricted Eating Speed Trials

Test Hypothesis

Using ½ and ¼ Baseline Eating Speed

Phase I: Baseline Eating Speed

10:00 minutes

Eating Speed (seconds per unit)

Number of Units Consumed

Grams & Calories Consumed

Meal Duration

Eating Speed; Froot Rings

Condition

Wk 2 Wk 3 Wk 4 Wk 5 R(1/2) R(1/4) Wk 11

Eat

ing

spee

d (s

econ

ds p

er F

root

Loo

p)

0

10

20

30

40

50

60

Average eating speed was 45 seconds per Fruit Ring

R(1/4)=180 secR(1/2)=90 secPhase II Rates

Eating Speed; Peanuts

Condition

Wk 2 Wk 3 Wk 4 Wk 5 R(1/2) R(1/4) Wk 11

Eat

ing

sp

ee

d (s

eco

nd

s p

er

pe

an

ut)

0

20

40

60

80

100

Average eating speed was 60 seconds per peanut

R(1/2)=120 sec R(1/4)=240 secPhase II Rates

Phase II: Restricted Eating Speed

Methods

Restricted Eating Speeds:

½ or ¼ of the baseline eating

speeds

10:00 minutes

Froot Loop Intake

Condition

Wk 2 Wk 3 Wk 4 Wk 5 R(1/2) R(1/4) Wk 11

Cal

orie

s co

nsum

ed

0

10

20

30

40

50

60

n.s.

n.s. n.s.

*

Slowing the eating speed DOES NOT reduce intake of

Fruit Rings.

Fruit Rings Intake

Meal Duration; Froot Loops

Condition

Wk 2 Wk 3 Wk 4 Wk 5 R(1/2) R(1/4) Wk 11

Mea

l dur

atio

n (s

econ

ds)

0

2000

4000

6000

8000

10000

12000

Meal duration was adjusted to compensate for restricted access to Fruit Rings.

Meal Duration: Fruit Rings

Eating Speed; Froot Rings

Condition

Wk 2 Wk 3 Wk 4 Wk 5 R(1/2) R(1/4) Wk 11

Eat

ing

spee

d (s

econ

ds p

er F

root

Loo

p)

0

10

20

30

40

50

60

Peanut Intake

Condition

Wk 2 Wk 3 Wk 4 Wk 5 R(1/2) R(1/4) Wk 11

Cal

orie

s co

nsu

med

0

10

20

30

40

50

60

Slowing the eating speed DOES NOT reduce intake of

Peanuts.

Meal Duration; Peanuts

Condition

Wk 2 Wk 3 Wk 4 Wk 5 R(1/2) R(1/4) Wk 11

Mea

l dur

atio

n (s

econ

ds)

0

1000

2000

3000

4000

5000

6000

7000

Meal duration is adjusted to compensate for restricted access to Peanuts.

Eating Speed; Peanuts

Condition

Wk 2 Wk 3 Wk 4 Wk 5 R(1/2) R(1/4) Wk 11

Ea

ting

sp

ee

d (

seco

nd

s p

er

pe

an

ut)

0

20

40

60

80

100

Hypothesis

The slower the rats eat, the less they will consume.NOT SUPPORTED

Contributions to the Literature• Seeley et al., 1993

– Intraoral glucose, liquid diet• Present study

– Solid foods of different macronutrient content• Both Studies: Rats compensate for meal

interruptions by increasing meal duration to maintain caloric intake.

• New Contribution: Caloric intake and eating speeds are not affected by macronutrient content of solid test foods.

Satiety Signals Terminate the Meal

Satiety Mechanisms

Human Studies

Eating speedFood intake in men, but not women (Martin et al. 2007)

Food intake (Yeomans et al. 1997)

Eating speed

Eating speedFood intake in women (Andrade et al., 2006)

Slow Down! You’ get full quicker, and you won’t eat so much.

Acknowledgments

Students in Biology 104B and 250A conducted this research

with guidance from Dr. Davis.

This research is an extension of work initially funded by the Fullerton Foundation.

Body Mass

Time

Wk 2 Wk 3 Wk 4 Wk 5 R(1/2) R(1/4) Wk 11

Bod

y m

ass

(g)

350

400

450

500

550

600

Froot Loop ratsPeanut rats