|05-17-2006, 07:27 PM||#1|
Been interested in IF for a while now, initially because I had good luck with Hofmekler's "Warrior Diet." The latest stuff in the Performance Menu (as well as Robb Wolf's enthusiasm) was enough to get me started. I fasted for 18 hours Tuesday and 17 hours today. I am trying to train in a fasted state right now, but am interested in discussions on whether or not that's optimal.
My goal: Maximal fat loss while maintaining performance. The hormonal manipulations possible within the IF scheme lead me to believe that this is one way to do it.
Here are a few things I came up with that I thought were interesting.
Glucose Tolerance and Skeletal Muscle Gene Expression in Response to Alternate Day Fasting
Leonie K. Heilbronn, Anthony E. Civitarese, Iwona Bogacka, Steven R. Smith, Matthew Hulver and Eric Ravussin
Objective: Alternate day fasting may extend lifespan in rodents and is feasible for short periods in nonobese humans. The aim of this study was to examine the effects of 3 weeks of alternate day fasting on glucose tolerance and skeletal muscle expression of genes involved in fatty acid transport/oxidation, mitochondrial biogenesis, and stress response.
Research Methods and Procedures: Glucose and insulin responses to a standard meal were tested in nonobese subjects (eight men and eight women; BMI, 20 to 30 kg/m2) at baseline and after 22 days of alternate day fasting (36 hour fast). Muscle biopsies were obtained from a subset of subjects (n = 11) at baseline and on day 21 (12-hour fast).
Results: Glucose response to a meal was slightly impaired in women after 3 weeks of treatment (p < 0.01), but insulin response was unchanged. However, men had no change in glucose response and a significant reduction in insulin response (p < 0.03). There were no significant changes in the expression of genes involved in mitochondrial biogenesis or fatty acid transport/oxidation, although a trend toward increased CPT1 expression was observed (p < 0.08). SIRT1 mRNA expression was increased after alternate day fasting (p = 0.01).
Discussion: Alternate day fasting may adversely affect glucose tolerance in nonobese women but not in nonobese men. The gene expression results indicate that fatty acid oxidation and mitochondrial biogenesis are unaffected by alternate day fasting. However, the increased expression in SIRT1 suggests that alternate day fasting may improve stress resistance, a commonly observed feature of calorie-restricted rodents.
Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism
Leonie K Heilbronn, Steven R Smith, Corby K Martin, Stephen D Anton and Eric Ravussin
Background: Prolonged dietary restriction increases the life span in rodents. Some evidence suggests that alternate-day fasting may also prolong the life span.
Objective: Our goal was to determine whether alternate-day fasting is a feasible method of dietary restriction in nonobese humans and whether it improves known biomarkers of longevity.
Design: Nonobese subjects (8 men and 8 women) fasted every other day for 22 d. Body weight, body composition, resting metabolic rate (RMR), respiratory quotient (RQ), temperature, fasting serum glucose, insulin, free fatty acids, and ghrelin were assessed at baseline and after 21 d (12-h fast) and 22 d (36-h fast) of alternate-day fasting. Visual analogue scales were used to assess hunger weekly.
Results: Subjects lost 2.5 ± 0.5% of their initial body weight (P < 0.001) and 4 ± 1% of their initial fat mass (P < 0.001). Hunger increased on the first day of fasting and remained elevated (P < 0.001). RMR and RQ did not change significantly from baseline to day 21, but RQ decreased on day 22 (P < 0.001), which resulted in an average daily increase in fat oxidation of ≥15 g. Glucose and ghrelin did not change significantly from baseline with alternate-day fasting, whereas fasting insulin decreased 57 ± 4% (P < 0.001).
Conclusions: Alternate-day fasting was feasible in nonobese subjects, and fat oxidation increased. However, hunger on fasting days did not decrease, perhaps indicating the unlikelihood of continuing this diet for extended periods of time. Adding one small meal on a fasting day may make this approach to dietary restriction more acceptable.
|05-17-2006, 08:21 PM||#2|
As long as I eat enough decent foods on the eat days I actually do better training in the fasted state. My two recent deadlift PR's were fasted and my times on the girls are better fasted as well.
If I don't eat enough or eat crap on the eat days I really notice it the next day. Lack of hydration is more noticeable too.
Hope this helps.
|05-18-2006, 09:11 AM||#4|
Kurtis and Steve,
Thank you both for the information. I have been doing the IF protocol for a week now; 24 fast followed by 24 eat day. It feels good so far, and every fact/ tidbit of info. helps.
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