1 Susan B. Roberts, PhD Professor of Nutrition & Professor of Psychiatry Director of the Energy Metabolism Laboratory, USDA Nutrition Center Scientific Staff Member in Pediatrics Tufts University and Tufts Medical School How, as individuals, should we approach nutrition and healthy weight control?
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How, as individuals, should we approach nutrition and healthy weight control?
How, as individuals, should we approach nutrition and healthy weight control?. Susan B. Roberts, PhD Professor of Nutrition & Professor of Psychiatry Director of the Energy Metabolism Laboratory, USDA Nutrition Center Scientific Staff Member in Pediatrics - PowerPoint PPT Presentation
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Susan B. Roberts, PhDProfessor of Nutrition & Professor of Psychiatry
Director of the Energy Metabolism Laboratory, USDA Nutrition CenterScientific Staff Member in Pediatrics
Tufts University and Tufts Medical School
How, as individuals, should we approach nutrition and healthy
weight control?
How To Weigh Yourself And Get The Most Accurate Results
“I can’t believe I was doing it wrong all these years.”
Some Statistics
Rates of obesity started rising in the mid-1980s- Adults: 2/3 now overweight or obese- Children: 1/5 now ow/obese and rising
51% adults diet in any given year
Using currently available diet methods, people who intentionally lose weight typically regain all lost weight
Energy Balance and Weight Control in Adults
Consumed Expended
kcal
/day
• To prevent obesity, energy intake = total energy expenditure
• Weight gain happens when intake > expenditure.
• Removing all the causes of weight gain creates neutral not negative energy balance.
• It’s easy to overeat, hard to undereat! The 2/3 population who are overweight/obese need effective methods for sustainable negative energy balance
2500
2000
1500
1000
500
3000
Love of good food!
Big portions
Stress-eating
Eating out a lot
Holidays & vacations
Lack of exercise
Pregancy-gain
Decreasing metabolism
Bod
y Fa
t (%
)
Net Energy Cost of Exercise Training Per Week (1000 kcal)1 2 3 4 5 60
45
40
35
30
25
20
15
10
Bod
y Fa
t (%
)
45
40
35
30
25
20
15
10
Regression of Change in Women
1 2 3 4 5 60
Summary of Changes in Body Fat in 50 Long-Term Exercise Intervention StudiesElder & Roberts. Nutr Rev 2007;65:1
• 1 hr/day absolute max achieved (less in women)
• Small effect exercise on fatness
• 1 hr/d of jogging -3.5% body fat over 6 mo (≈6 lb weight)
Regression of Change in Men
What Happened?
1000
1500
2000
2500
3000
19751980
19851990
20002005
1995Per
Cap
ita F
ood
Sup
ply
Cor
rect
ed fo
r Was
te(k
cal/d
ay)
• Increase of 564 kcal/d in food supply.• 2 foods account for most of the increase: - high fructose corn syrup - oil• 4 more contribute a bit: - flour - cheese - shortening - edible beef tallow
• What didn’t increase: beef, seafood, candy, chocolate, chips, cream (and ice cream and frozen desserts decreased 13%)
•
A problem of energy intake or energy expenditure?
Weight loss and prevention of weight regain require reducing energy intake relative to energy expenditure. Given the 500+ calorie increase in energy intake since 1975, a decrease in energy intake is easily justified as practical solution
Amounts of exercise required to reduce BMI values to a healthy range unlikely to be achievable and therefore hard to justify as practical solution
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Is reducing energy intake a society problem or and individual problem?
Restaurants as one example of our food environment, and their impact broadly
considered
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Multi-Site Study of Randomly-Selected Restaurant FoodsUrban et al. JAMA 2011
• Study of 269 randomly selected restaurant foods from MA, AR, IN• Average stated calories were accurate BUT low calorie foods in sit-down restaurants
contained 7% more calories than stated.• Sides on average contained more calories than the entrée they accompanied.• Estimated impact on body weight if self-monitoring energy intake: ≈+10 lb/year
Excess Energy Intake Relative to Requirements in Most Restaurant Meals
(Urban et al, in preparation)
500 kcal
• Study of 170 restaurant meals from 9 most popular ethnic categories in 36 randomly selected restaurants in Greater Boston area
• Average stated calorie contents were 1276 kcal.
667 kcal
• Represents 2.0-2.5 times healthy meal size for maintaining energy balance, and ≈100% daily energy intake for individual trying to lose weight.
Why do humans eat the way they do and like the things they like?
• Moviegoers were given free popcorn - fresh or stale - medium or large.
• Amount consumed was significantly greater for larger
portions even when the popcorn was stale.
Bad Popcorn in Big Buckets(Wansink & Kim, 2005)
AVAILABILITY: eating just because its there
Underestimation of energy content of large portions (Chandon & Wansink, 2007)
Small, medium and large meals were chosen at McDonald’s and Subway and volunteers estimated energy intake.
Greater underestimation of energy intake with larger portions in both restaurant meals
Est
imat
ed e
nerg
y in
take
, kca
l/por
tion
Portion energy intake, kcal/portion
An Optimal Weight Control Diet Satisfies The Three Distinct Neurological Systems That Regulate Feeding Behavior
Hunger-Satiety(1º hypothalmus)
Hedonic Pleasure(1º orbitofrontal cortex)
Reward ( “need”)(1º nucleus accumbens)
Hunger & Satiety Reward & Pleasure
An optimal weight control diet will give a sustainable balance between reward/pleasure and hunger/satiety
Afferent signals (body to brain) report bodily needs to hunger-satiety and reward/pleasure centers:• Vagal nerves from
stomach & lower GI• Gut hormones from
stomach & ileum • Circulating nutrients
(glucose & FFA in blood)
• Fat cell hormones such as leptin
• Post ingestive conditioning (eg dopamine reward in midbrain) anticipates and maintains reward for eating high calorie foods and familiar foods
And trigger the ‘cephalic phase of digestion’ in unconscious lower brain which:• Increases real
• Accelerates GI motility (more rapid digestion speeds return of hunger and desire to eat again sooner
The senses report what’s out there to hunger-satiety and reward/pleasure centers: • Sight • Smell • Taste
internal control
external control
Neurological rather than psychological explanations
What it all means…
• In effect, our environment controls:- our metabolism- our hunger- our synthesis of neurotransmitters such as dopamine that keep us eating- when there is more food we eat more to feel adequately satisfied
• People feel guilty about weight gain, but for the most part we overeat to feel we are eating normally, because environmental control over hunger and metabolism happens in our lower unconscious brain
Explains why an increasingly toxic food environment made us eat an extra 564 kcal/d of HF corn syrup and oil since 1975!
• Accept that the obesity crisis won’t be solved without much more federal government involvement.
• Get economists and nutrition scientists together to work out how you can change the food environment. Introducing healthy choices won’t be enough!
• Think big. This is not just about regulating school food. Could fuel emission standards be a model for restaurants and food companies? Federal junk food taxes? Subsidized weight programs?
• Continue ongoing efforts to eliminate: - false claims of rapid weight loss - food advertisements that encourage overeating
• Would take charge. Diet sensibly. Make their work food environment better for weight control. As parents, get involved in school food.
Consumers
Government
• Would refuse advertising for foods that promote obesity and untested gimmicks and diets falsely implying more weight loss that typically achievable.
Media
In the ideal world…
Individual Energy regulation: influenced by several factors
HUNGER: the need to feel satisfied
AVAILABILITY: eating just because its there
CALORIE DENSITY: what we like most
VARIETY: passive overeating and sensory specific satiety
FAMILIARITY: maintaining established eating habits (just because they are familiar)
Fiber Glycemic Index Protein Volume
Current Paleolithic Ratio P:C
Folate 0.08 0.12 1.5
Vit. A 2.1 5.7 2.7
Vit. C 24 201 8.4
Vit. E 3.5 10.9 3.1
Iron 4.9 28.5 5.8
Ca 392 653 1.7
Zinc 5.3 14.5 2.7
Fiber (g/d) 15 104 6.9
Western vs. Paleolithic Diet (Eaton et al. 1997)
(mg/d)
Dietary factors thatreduce hunger and/or
increase satiety relativeto energy intake
Hunger: Not All Calories Are Equal
Liquid calories have the oppositeeffect of no satiety despitehigh calories
Effects of a Combined Nutrition and Behavioral Weight Loss Intervention in Worksites
(Salinardi, Batra et al, in preparation)
A RCT of a 6 mo worksite weight loss program was conducted in 4 worksites (2 for profit, 2 non-profit) with 100-500 employees in Greater Boston.
Control sites were wait listed for the program.
Individuals in intervention sites with BMI >25 kg/m2 could sign up for a comprehensive behavioral intervention involving weekly group meetings for 16 weeks and then biweekly meetings for 8 weeks.
14% total employees enrolled and 89% of enrollees completed the 6 month program. Weight loss was significant in both intervention sites.
0 6 10 16 20 24-12
-10
-8
-6
-4
-2
0
2
4
Weeks of Program
Wei
ght L
oss (
% In
itial
Wei
ght)
Summary
Positive and negative energy balance are different states: easy to be in positive energy balance, hard to be in negative energy balance.
Implication 1: unlikely to resolve the obesity epidemic with community-level prevention measures alone
Implication 2: need greater emphasis on developing effective, sustainable, cost-effective weight loss interventions for the 2/3 population already overweight or obese