Calorie restriction Flashcards
Discuss calorie restriction
- Reduction in energy (calories) without a deficit of micro and macronutrients to avoid malnutrition and deficiencies
- Negative energy balance
- Can decrease the biological rate again and increase the average and maximal life span
What chronic diseases might calorie restriction help?
- Cancer
- Vascular disease
- Diabetes
- Autoimmune diseases
- Neurodegenerative diseases
Some research/ evidence
What is the Okinawa study?
What was found?
Japanese island, 1970’s study. Found that there was a lower prevalence of CVD and high mortality rates than in mainland Japan.
Looked at dietary records and found that school children had an energy intake <62% lower than mainland –> over-estimated, more likely 20-30%. Still a substantial deficit.
In adults, there was an energy deficit of <20% in mainland japan and <40% in America.
The majority of occupants were farmers, had high physical activity occupations, and were more likely to be more active than those on the mainland.
Didn’t measure stress levels.
The rate of death of Okinawans between the age of 60-64 was 50% lower than Americans
Cardiovascular and cancer in Okinawa were 60% lower than the rest of Japan.
Those who move to maintain have mortality rates high than those who remain on the island - environmental factors could play a larger part than genes.
What is the Biosphere 2 study?
What was found?
A group of people lived in a controlled environment where they grew and made their own food.
Diets were restricted by 750 kcal.
The experiment was stopped after 2 years due to a leak that jeopardized their ability to grow and make food.
After 2 years it was found that
- BMI males <19% with an average of 19.3 +- 0.9km/m
- BMI females <13% with an average of 18.5 +- 1.2kg/m
A decrease in
- blood pressure
- fasting glucose
- insulin
- cholesterol
- t3
- white blood cells
What is the CALERIE study?
What was found?
Comprehensive Assessment of Long-Term Effects of Reducing Calorie Intake
3 groups
- 12 months, 25% negative energy balance, healthy individuals, overweight, 24-45 years old
- 6 months, 25% in overweight men and women aged 25-50
- 12 months, 20% energy restriction in 50-60 year old healthy overweight men and women.
Findings:
6 months:
Significant decrease of…
- Body weight
- Body temperature
- Body expenditure
- Body fat mass, visceral and subcutaneous adiposity
- Fasting insulin and glucose
12 months:
Significant decrease of…
- 10.7% of body weight (compared to baseline)
- BMI from 27.2 to 24.4
- Visceral and subcutaneous adiposity
- Circulating leptin
- Fasting insulin and glucose
- Improved insulin sensitivity
The main difference experienced occurs between 3-6 months of dietary intervention.
- Most important outcomes in terms of CV health
With most dietary interventions this is the case.
Why do the most significant dietary changes occur during 3-6 months?
The body adapts to changes so after 6 months the body has adapted. Need to change stimulus for consistent long-term changes. Intervention change is needed for a change in benefits.
Benefits decrease will time if the stimulus stays the same, 3-6 months is the time period where the intervention is taking place and the body is responding to it as it is not yet adapted to the intervention/ stimulus.
Is there an optimal diet for weight management and metabolic health?
Most effective
- very low-energy diet
Diet and exercise
- not causing a huge change, requires a change in stimulus to prevent body adaptations, for both diet and exercise.
Long term not much difference between the 2
How does calorie restriction have an effect on oxidative stress?
Reducing energy intake it causes a decrease in resting metabolic rate which causes a decrease in oxygen consumption.
Lower oxygen consumption leads to less reactive oxygenous species (ROS) which overall decreases the level of oxidative stress in the body.
Oxygen demands depend on body mass, more bm = more oxygen, more adipocytes.
How does calorie restriction have an impact on the production of ROS?
Lower energy intake means there is less ATP in cells causing a decrease in the ATP: ADP-AMP ratio.
This causes an up-regulation of the expression of genes for endogenous antioxidants in cells.
This increases antioxidant levels in cells.
What are some possible adverse effects of calorie restriction?
- Hypotension
- Fat tissue (amenorrhea and infertility)
- Bone density (osteoporosis)
- Muscle mass
- Immunology (wound healing)
- Hair loss
- Fainting
- Eating disorders (AN, BED)
- Depression
- Social isolation
- Anxiety
What effect does tissue damage have on oxidative stress?
High body mass and tissue damage from adipocytes can cause an immune response which causes oxygen demands to increase. This increases the level of oxidative stress.
ATP: ADP-AMP ratio increases due to overeating (obesity), increase production of ATP in cells, and down-regulates the expression of genes for endogenous antioxidants. Deflections of endogenous antioxidants.
Level of antioxidants is lower in those with high amounts of adipocytes.
