Glycemic instability and spontaneous energy intake: association with knowledgebased work

1
Glycemic instability and spontaneous energy
intake association with knowledge-based work

• Jean-Philippe Chaput, Vicky Drapeau, Paul
  Poirier, Normand Teasdale, Angelo Tremblay
• June 6, 2008

2
Evolution of man

• I am not surprised that people are getting fat.
  
• I am surprised that some people remain lean .
• Susan Jebb
• MRC Human Nutrition Research Center
• (Cambridge)

3
Evolution of man
4
Physical work vs.
Mental work
Glucose FFA
Glucose
ATP
Heat
5
Objectives

• To determine if KBW induces an acute excess in
  energy intake.
• To determine if the postulated orexigenic effect
  of KBW results from a perturbation in glucose
  homeostasis.

6
Subjects

• 14 healthy Laval University female students.
• Aged 20 to 30 years.
• BMI ranging between 20 and 30 kg/m2.
• Non smokers.
• Exempt of eating disorders.
• Sedentary or moderately active ( 3 hours of
  physical activity/week).

7
Methods

• Repeated measures/within-subjects design.
• 3 conditions 1) resting in a sitting position,
  2) reading-writing and 3) performing a
  comprehensive battery of computerized tests.
• Conditions randomly assigned to subjects.
• 45 minutes for each condition.
• Blood sampling at every 8 minutes.
• Ad libitum buffet after each condition.

8
General overview
8h00
10h30
11h30
Standardized breakfast
Buffet
Test
9
Descriptive characteristics of women

• Variables
• Age (years) 22.8 ? 2.3
• Body weight (kg) 61.9 ? 9.6
• BMI (kg/m2) 22.4 ? 2.5
• Waist circumference (cm) 73.9 ? 9.2
• Three-Factor Eating Questionnaire
• Cognitive dietary restraint 4.3 ? 3.1
• Disinhibition 5.6 ? 2.4
• Susceptibility to hunger 4.2 ? 3.3
• State-Trait Anxiety Inventory
• Anxiety-trait 39.1 ? 8.0
• Cohens Perceived Stress Scale 17.2 ? 8.2

Data are mean SD.
10
Mental workload quantification

• Control Reading-writing
  Test-battery
• NASA-Task Load Index1 18.5 ? 12.8
  59.2 ? 15.4 63.3 ? 16.2
• Reaction time (ms) 2 617 ? 84
  857 ? 193 883 ? 136

p lt 0.01 versus control values. 1Questionnaire
assessing the overall perceived
workload. 2Secondary task assessing the degree
of mental solicitation.
11
Heart rate variability assessment

• Control Reading-writing
  Test-battery
• Heart rate (beats/min) 71 ? 9
  79 ? 8 80 ? 9
• Systolic BP (mm Hg) 102 ? 9
  110 ? 8 110 ? 8
• Diastolic BP (mm Hg) 62 ? 8
  70 ? 6 71 ? 10
• HRV indices (Holter)
• Ln LF (ms2) 2.77 ? 0.78
  2.94 ? 0.79 3.02 ? 0.81
• Ln HF (ms2) 2.71 ? 0.64 2.38 ? 0.61
  2.37 ? 0.64
• LF / HF 1.03 ? 0.67 1.24 ? 0.59
  1.28 ? 0.61

p lt 0.05 versus control values. p lt 0.01
versus control values.
12
Energy intake in the buffet-type meal

• Control Reading-writing
  Test-battery
• Total energy intake (kcal) 860 ? 223 1063
  ? 243 1113 ? 244
• Lipid (kcal) 401 ? 178 514 ? 161
  527 ? 138
• Lipid () 46.6 ? 10.1 48.3 ?
  10.6 47.3 ? 16.1
• Carbohydrate (kcal) 338 ? 116 424 ?
  120 439 ? 162
• Carbohydrate () 39.3 ? 8.7
  39.9 ? 7.4 39.4 ? 8.1
• Protein (kcal) 121 ? 44 125 ? 38
  147 ? 55
• Protein () 14.1 ? 4.7
  11.8 ? 6.8 13.3 ? 3.9
• Desserts (kcal) 180 ? 99 288 ? 83
  299 ? 108

p lt 0.05 versus control values.
13
Appetite sensation markers (VAS)
14
Compensation for the rest of the day

• Control Reading-writing
  Test-battery
• Total energy intake (kcal) 1143 ? 340
  1168 ? 332 1206 ? 412
• Lipid (kcal) 431 ? 202 434 ? 271
  446 ? 260
• Lipid () 37.7 ? 11.9 37.2
  ? 16.8 37.0 ? 12.6
• Carbohydrate (kcal) 516 ? 178 565 ?
  219 544 ? 238
• Carbohydrate () 45.1 ? 13.3
  48.4 ? 17.9 45.1 ? 18.5
• Protein (kcal) 196 ? 74 169 ? 71
  216 ? 84
• Protein () 17.2 ? 5.6
  14.4 ? 5.4 17.9 ? 5.9

Not significantly different between conditions.
15
Glycemia over 45 minutes
p lt 0.01 vs. control values
Glucose instability sum of absolute changes
between each
time of blood collection.
16
Insulinemia over 45 minutes
p lt 0.01 vs. control values
17
Cortisolemia over 45 minutes
p lt 0.05 versus control values.
18
Conclusion

• This study showed that KBW acutely induces a
  significant increase in spontaneous energy intake
  and promotes an increased fluctuation in plasma
  glucose and insulin levels.
• As proposed by the glucostatic theory, energy
  intake may be triggered with the goal of
  restoring glucose homeostasis.

Jean Mayer (1920-1993)
19
Thank you !!!

• This research was funded by the Canada Research
  Chair in Physical Activity, Nutrition, and Energy
  Balance and the Canadian Institutes of Health
  Research. Heart rate variability measurement was
  made possible through support from the Fonds de
  la recherche en santé du Québec (FRSQ).