OnCore Nutrition - Two Peas in a Podcast
Episode 17: Intermittent fasting level: expert
Episode Summary
In episode 9 we discussed IF 101. For those who want a little more nitty gritty detail, this ep is for you! To cover: IF for weight loss: Calorie deficit vs IF Circadian rhythms Fasting and cancer - where is the research at? Fasting and diabetes
Episode Notes
SHOW NOTES
Australian Bushfire Donations:
Wires
Red Cross
CFA
Food Bank
OnCore Intermittent Fasting Guides - https://store.oncorenutrition.com/collections/all
Physiological benefits
http://oncorenutrition.com/to-fast-or-not-to-fast/
Coffee https://www.ncbi.nlm.nih.gov/pubmed/28177691
Practicalities / sustainability / contraindications
http://oncorenutrition.com/the-fast-and-the-furious/
Guides: http://oncorenutrition.com/intermittent-fasting/
https://store.oncorenutrition.com/collections/all
IF and calorie deficit similar weight loss outcomes
Some find IF mentally challenging than consistent cal deficit, others find the opposite
- Science currently unclear if IF vs CR is responsible for the body composition changes and good health.
- Why the evidence is unclear is that many studies have been conducted in animal based models which we know has limitations
- Human studies have been relatively poor (e.g. short duration) and mainly focused around weight loss (in the short term) rather than aging and disease risk.
- https://www.ncbi.nlm.nih.gov/pubmed/28459931
- 100 obese participants - 6 women and 14 men, aged between 18–64 (the mean age was 44). Note they did not have metabolic conditions (e.g. T2DM).
- Looked at different dieting patterns
- Alternate-day fasting - consumed 25% of their daily energy requirements on fast days and 125% of their daily requirements on alternate days.
- Calorie restriction diet plan where the subjects consumed slightly less than their energy need (~75%) each day.
- Another group with no dietary intervention.
- Results: With regard to the two dieting groups, they both lost a similar amount of weight and showed no significant difference regarding, blood pressure, heart rate, triglycerides, fasting glucose, fasting insulin, insulin resistance & inflammatory markers at month 6 or 12.
- Of note there was a higher drop out rate within the alternate fasting day group, which may indicate adherence and consistency may be a challenge with this method,
- Our recommendation: No real difference between the fasting vs calorie restriction group. There is no magic pill when it comes to weight loss. Do what works best for you and work with a professional who understands your needs.
- https://onlinelibrary.wiley.com/doi/full/10.1111/j.1467-789X.2011.00873.x
- Intermittent CR and daily CR diets appear to be equally as effective in decreasing body weight, fat mass, and potentially, visceral fat mass. However, intermittent calorie restriction protocols may be superior in that they help conserve lean mass at the expense of fat mass. More research + longer term studies are required.
Circadian rhythms
According to your circadian rhythm, nighttime is for resting, not eating.
On average - we eat every 3hrs and 6 minutes and for a duration of approx 15hrs per day
Mice that eat in opposition to their circadian rhythm gain significantly more weight than mice that only eat during waking hours, even if they eat the same amount of food. Not all studies in humans support this notion.
At night, you may be more likely to choose unhealthy, calorie-dense foods.
The first RCT in humans was published half way through 2019 to determine how meal timing affects 24-hour energy metabolism when food intake and meal frequency are matched
- Small n= 11 men + women aged 25-45
- two groups of people who ate the same three meals per day for 4 days but with different timings: the early time-restricted feeding (eTRF) schedule and the control schedule.
- 8am - 2pm (18hr fast) vs 8am - 8pm (12hr fast)
- On the fourth day, 24‐hour energy expenditure and substrate oxidation were measured by whole‐room indirect calorimetry, in conjunction with appetite and metabolic hormones
- No effect on 24hr energy expenditure
- May enhance fatty acid oxidation - i.e. using fat for fuel rather than carbohydrates
- TRF Decreased ghrelin levels, enhanced fullness, decreased desire to eat
- Meal‐timing interventions facilitate weight loss primarily by decreasing appetite rather than by increasing energy expenditure. eTRF may also increase fat loss by increasing fat oxidation.
https://onlinelibrary.wiley.com/doi/full/10.1002/oby.22518
Another study 6am-7pm
- Nothing unless than the hrs to adhere to - no type, amt of food, no record keeping
- Ate fewer calories and lost weight
Another study
Another study
- 3 meals vs 1 meal - same calories
- Normal-weight subjects are able to comply with a 1 meal/d diet. When meal frequency is decreased without a reduction in overall calorie intake, modest changes occur in body composition, some cardiovascular disease risk factors, and hematologic variables. Diurnal variations may affect outcomes.
- Both late eating
- Improvement in weight loss, but blood pressure and chol levels suffered!
- https://www.ncbi.nlm.nih.gov/pubmed/17413096
Early TFR
- eTRF (6-hr feeding period, with dinner before 3 p.m.) or a control schedule (12-hr feeding period) for 5 weeks and later crossed over to the other schedule.
- eTRF improved insulin sensitivity, β cell responsiveness, blood pressure, oxidative stress, and appetite.
- We demonstrate for the first time in humans that eTRF improves some aspects of cardiometabolic health and that IF's effects are not solely due to weight loss.
- https://www.ncbi.nlm.nih.gov/pubmed/29754952
- Even 10-11hrs TRF beneficial - weight loss, improved energy levels, improved sleep
https://www.ncbi.nlm.nih.gov/pubmed/31808043
https://www.ncbi.nlm.nih.gov/pubmed/26693661
IF and breast cancer risk
https://www.ncbi.nlm.nih.gov/pubmed/26305095
These findings suggest that eating more frequently, reducing evening energy intake, and fasting for longer nightly intervals may lower systemic inflammation and subsequently reduce breast cancer risk. Randomized trials are needed to validate these associations.
Breast cancer prognosis
- 2413 women (mean [SD] age, 52.4 [8.9] years)
- mean (SD) fasting duration of 12.5 (1.7) hours per night.
- fasting less than 13 hours per night was associated with an increase in the risk of breast cancer recurrence compared with fasting 13 or more hours per night but wasn’t associated with mortality rates
NO RCTs YET!
https://www.ncbi.nlm.nih.gov/pubmed/27032109
Diabetes
- Very small study n = 3 men who had had type 2 diabetes for 10-25 years.
- Medical supervision
- Fasted every other day or 3 days a week.
- Within a month, all of the men were able to stop taking insulin. And in less than a year, they were able to cut down on or stop other diabetes medications.
- Another small study, 10 obese men with type 2 diabetes followed a time-restricted eating plan. They improved their fasting glucose and lost weight over 6 weeks.
- Bigger studies are needed to confirm those findings and to see how long the results last
- The American Diabetes Association notes that if you’re overweight or obese, weight loss can help lower your HbA1c level (a gauge of your blood sugar control over the last 2-3 months) and lower your risk for heart disease.
Important to:
- Talk to Dr/endocrinologist first
- Adjust your insulin
- Monitor for lower BGL
- Beware of large carbohydrate load on first meal
Cell Metabolism: “Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes."
BMJ Case Reports: “Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin."
Joslin Diabetes Center: “Yom Kippur and Diabetes.”
BMJ Open Diabetes Research & Care: “Recommendations for management of diabetes during Ramadan: update 2015."