Are you claiming that there anabolic response to fasted training is superior to someone who trains in the fed state?
I should also go back and question the second source I posted; it stated that fasted training led to a decrease in bodyweight and body fat whereas fed training only resulted in a drop in bodyweight. Is it claiming that all the weight lost was lean tissue when performing aerobic training in the fed state? Doubtful.
I dont think the training is going to impact the bodyfat or weightloss. the overall caloric deficit would be the major factor regarding that. Depletion training (high rep/hypertrophy) training could aid in glyocgen depletion, but who is to say that is really the key factor to fatloss or fatloss for training. We have seen in real life that hypertrophy training while dieting can be a disaster and cause to a ton of muscle loss if one is not training heavy when they do diet. So it is doubtful as much science as we do read i doubt we have one specifically on bodybuilders or that does compare the fed to fasted state for our exact research we are trying to find since most reserach is done in either 1) Rats, 2) overweight subjects, or 3) People who have messed up caloric intakes to not really match their goal which skew the end result.
Anabolic response:
Insulin Response and Nutrient partitioning:
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"GLUT4: Glucose transporter type 4 is a protein responsible for insulin-regulated glucose transport into the muscle cell. It increased by a whopping 28% in F but only 2-3% in C (not mentioned in the paper but this is my estimate based on the graphs). This partly explains why F saw superior results in regards to glucose tolerance and insulin sensitivity.
Since GLUT4 is triggered by AMPK, which is increased when glucose availability is low, i.e. during fasted training, one would assume the GLUT4 increase could then be explained by an increase in AMPK. This was found to be true: AMPK increased by 25% in F, which correlated closely with the increase in GLUT4 content."
Metabolic enzymes: Very fittingly, the same group of enzymes that were investigated in the study I covered in "Fasted Training Boosts Endurance and Muscle Glycogen" were looked at here.
Interestingly, changes in citrate synthase and HAD, two markers for fuel-utilization efficiency, were not different between F and C. However, two other important markers for glucose and fat metabolism, FAT/CD36 and CPT1, were increased by ~30% in F. C saw no increase at all.
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Body composition: Now this is very interesting. Despite overfeeding the subjects with 1000 calories or more, F only gained 0.7 kg. From a scientific standpoint, this is deemed insignificant. That is, the gain could likely be attributed to chance or, very likely, fluctuations in body weight due to increased muscle glycogen. This lack of weight gain in F could not be explained by the training regimen. They were still overfed by 15-20% when accounting for the extra activity. This left the subjects with a theoretical surplus of 650 calories per day, on average, which should have resulted in weight gain equivalent to ~3.5 kg after six weeks.
What about C? They gained 1.4 kg, twice as much as F, despite doing the same amount of exercise and consuming the same amount of calories and macronutrients.
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More from Martin:
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The main findings of the present study were that: training in an overnight-fasted state enhances storage of muscle glycogen compared to training in the fed state; skeletal muscle of men and women respond differently in terms of oxidative activity to training in the fed and overnight-fasted state; and peak VO2 and peak power improved more when training in the fasted state compared to the fed state."
Questioning the dramatic increase (+54.7%) in muscle glycogen in the fasted group, the researchers were not able to find an answer based on unexpected confounders or behaviors between groups. Muscle biopsies were taken at the same time and there were no difference in diet in between groups.
"...it is highly likely that the differences in glycogen stores between groups reflect the training intervention and not exercise timing or pre-biopsy diet."
Moreover, these results are in line with a prior study that found similar results for fasted training.
"Importantly, our findings correspond to that of De Bock et al. confirming that training whilst circulating CHO levels are low increases the capacity to accrue glycogen in the trained muscles."
What might be the reason for the different effects between genders on oxidative enzymes? As mentioned previously, differences in fuel utilization. Males rely less on intramuscular triglycerides and fatty acids and more on glucose, while females burn a higher percentage of fat at any given exercise intensity. But why fed state training would then be more beneficial for females when it comes to "oxidative adaptation" requires further investigation.
More on fasted training and protein synthesis:
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In this study, subjects were split into two groups that were trained on two occasions separated by three weeks. The three-week rest period between sessions served as a "washout" period, in order to make sure that the prior session didn't interfere with the results obtained during the second test.
The workouts were fairly basic whole-body sessions: 3 x 8 in seven movements such as bench press, overhead press, curls and leg press.
One of the sessions (F) were performed on an empty stomach after an overnight fast.
The other session (B) was performed in the fed state. Subjects were given a breakfast of 722 kcal composed of 85% carbs, 11% protein and 4% fat, and training was initiated 90 minutes after the meal.
After the weight training session, both groups rested for 4 hours. At the one- and four-hour marks, muscle biopsies and blood tests were obtained . Participants were also also given a recovery drink to sip each hour during the rest period.
Results revealed that the F session had twice as high levels of p70s6k in comparison to the B when measured at the one-hour mark post-workout. Other myogenic transcription factors were also higher at this point, though not quite as pronounced as p70s6k. At the four-hour mark, the differences between the two groups had evened out.
Among other things, increased levels of p70s6k may lead to a faster transport of amino acids into the muscle cell membranes, which should lead to a more rapid and potent anabolic response to post-workout nutrient ingestion. The effects seen on the other myogenic signaling mechanisms could also affect muscle growth through other pathways.