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The Response to Long Term Overfeeding in Identical Twins

Presented by: Mujan Noroozian

Claude Bouchard, PH.D., Angelo Tremblay, PH.D., Jean Pierre Despres, PH.D., Andre Nadeau, M.D., Paul J. Lupien, M.D., Germain Theriault, M.D., Jean Dussault, M.D., Sital Moorjani, PH.D., Sylvie Pinault, M.D., and Guy Fournier, B.Sc.

Background

Study done

“To determine whether there are differences in responses of different persons to long term overfeeding”

Hypothesis:

There are differences & there is a possibility that genotypes are involved in these differences.

Bouchard, C., Fournier, G., Tremblay, A., Després, J., Nadeau, A., Lupien, P. J., . . . Pinault, S. (1990). The response to long-term overfeeding in identical twins. The New England Journal of Medicine, 322(21), 1477-1482. doi:10.1056/NEJM199005243222101

Sample

• 24 sedentary young men (12 pairs of Monozygotic twins)

• Monozygosity established on

• Basis of questionnaire• Physical appearance• Similarity of their antigens • & enzymes


Inclusion/Exclusion

• Between ages of 19-27 years of age

• Raised and living together before study

• Their health history & family health history had stipulations


Testing

Period of 18 months4 pairs of twins studied at a time

Men housed in closed area with 24 hr supervision

Each man in unit for 120 consecutive days

1. Base Line Test Period

2. Testing Before Period

3. Overfeeding Period

4. Testing After Period


Base Line Testing

14 Days

• Body weight, Skin-fold thickness, Body density measured daily

• Men ate freely

• Energy content of body fat about 9300 kcal/kg

• Energy content of lean tissue about 1020 kcal/kg

★The body energy content was the sum of these two

• Avg. nutrient composition of food was 52% CHO, 34% lipid, and 14% protein

Testing Before & After Overfeeding Period3 Days

• Measured resting metabolic rate & thermic effect of food

• Underwater weighing

• Adipose tissue biopsies

• Exercise tolerance testing


Overfeeding Period

100 days

• A Diet 1000 kcal more than base line diet for 6 days/week

• Day 7 they had the base line number of calories

• Total excess energy intake of 84,000 kcal

• Nutrient composition: 50% CHO, 35% fat, and 15% protein

• 3 meals and 1 snack a day

• Physical activity limited

• Body weight, skin-fold thickness (q 5 days), & waist/hip circumference (q 25 days) measured

Statistical Analysis

ICC: Intraclass correlation coefficiant

• Close to 1.0 indicates perfect w/in pair resemblance to overfeeding

• Close to 0 implies there is no w/in pair resemblance in response to treatment

F Ratio

• High # indicates high ratio of variance between pairs to variance w/in pairs.

• Low # (close to 1) indicates that variance in response between pairs & w/in pairs are comparable.

Overall Results

Increases

• Body weight (avg. gain=8.1 kg)

• Fat mass & fat free mass

• Sum of skin-fold thickness (about 70%)

• Mean resting heart rate (from 58 to 63 beats/min)

• Diastolic blood pressure (from 66 to 70 mm Hg)


Results

Regional Fat Distribution

Estimated by several methods

• Amount of subcutaneous fat increased on trunk & limbs

• Trunk to limb ratio increased from 1.26 to 1.60

• Waist & Hip circumference increased

• Ratio of waist to hip circumference also increased


Trunk & Abdominal Fat

Measured by CT

• Increase in adipose tissue surface area in all subcutaneous & visceral sections


Results

Discussion

Results of this study allow assessment of the response of…

• Excess total body fat

• Excess trunk or abdominal subcutaneous fat

• Excess abdominal visceral fat

…to long term overfeeding


Discussion

• Changes in the men’s bodies varied between the high & low weight gainers.

• more fat in truncal-abdominal area

• Surplus intake of energy over a long time doesn’t cause identical responses in respect to body mass, body composition or regional fat distribution

• Increases in total body fat correlated with gains in truncal subcutaneous fat only

• Overall there was more variance between pairs of twins than within pairs


Critique

• Further studies would need to be done in order to see why some people more prone than others to store fat on the trunk vs. abdominal cavity

• Wide differences between the people in response to long term overfeeding

Conclusion

1. There is a resemblance between identical twins in response to overfeeding

• Due to a person’s genotype

• All subjects in this study given same treatment conditions

2. Individual differences due to undetermined genetic characteristics


How it will affect dietetic practice• This study shows that a person’s genes determine

body weight & body composition

• With a negative energy balance & exercise, a person can reduce their weight

• To keep weight, constant maintenance is needed for upkeep

• Client’s health should be the most important thing• Important to help set realistic goals for your clients


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