Fat and protein metabolism

[Orangutan]

I've recently read some studies saying fats are necessary for effective protein metabolism. Mainly the case is concerning post workout protein drinks. Some studies suggest the protein (mostly whey) should be mixed with whole organic milk to ensure proper metabolism. However, since the addition of fat will slow down digestion this would in turn hamper the quick absorption of protein needed to combat the catabolic state. Does anyone have any ideas on this? If fat is in fact needed to get the best effect from the drink, would unsaturated lipids such as olive oil work as well as the saturated fat found in milk?

[ATZ]

A couple of studies show whole milk to be better PWO than skimmed, the mechanism for this is unknown, but could be due to your protein metabolism theory above. Personnally don't worry about the "catabolic state", its overrated and a myth used by supp companies to ensure your gulping down their next patented recovery product. The fat won't impact absorbtion to any great degree.

As long as your fed within a hour of working out, either with a shake or wholefoods you should be good.

[ATZ]

I'll see if I can dig the study out I'm referring to also.

[ATZ]

Quote

Elliot and colleagues compared the effect of fat-free milk, whole milk, and a higher dose of fat-free milk (to match the calories of the whole milk) taken 60 minutes post-resistance exercise.24 Whole milk was superior for increasing net protein balance. Interestingly, the calorie-matched dose of fat free milk containing 14.5g protein, versus 8.0g in the whole milk (an 81% advantage), but still got beaten. The investigators speculated over the possible mechanisms behind the outcome (insulin response, blood flow, subject response differences, fat content improving nitrogen retention), but end up dismissing each one in favor of concluding that further research is necessary to see if extra fat calories ingested with an amino acid source will increase muscle protein synthesis. Lingering questions notwithstanding, post-workout milkfat was the factor that clinched the victory – at least in overnight-fasted subjects

From commentary taken on this study:

Elliot TA, et al.
Milk ingestion stimulates net muscle protein synthesis following resistance exercise.
Med Sci Sports Exerc. 2006 Apr; 38(4):667-74.

[ATZ]

The above was taken from an article by Alan Aragon on fat and insulin effects postworkout, the whole article is worth sharing tbh:

POST-EXERCISE

Effect on 24-hr Glycogen Resynthesis

A common recommendation in sports and fitness circles is to avoid or minimize fat intake immediately after training, a time popularly called the "anabolic window" or "window of opportunity". The fear of post-exercise fat is based on its ability to slow gastric emptying, and thus slow the release of glucose into circulation which in turn reduces insulin response and glycogen resynthesis. Is this a valid concern? First of all, exercise for varies in its ability to tap-out glycogen stores. Resistance training, as it’s commonly done for strength, bodybuilding, or general fitness, is not glycogen-depleting in fed subjects on moderate-volume protocols. To illustrate this, Roy and Tarnopolsky observed 9 sets of 10 reps at 80% of 1 rep max to cause an average muscle glycogen decrease of 36%.16 It’s important to note that subjects consumed 3 mixed meals approximately 3 hours apart leading into the trial, which was 3 hours after their 3rd meal. A fasted scenario would have been more glycogen-depleting, as would a more voluminous protocol. The interesting find of this trial is that there was no difference in glycogen synthesis rate between a mixed post-workout drink (66% carb, 23% prot, 11% fat) and a 100% carb drink. Both drinks had the same proportion of carb types, so that potential confounder was controlled.

In another example of the triviality of worrying about fat’s inhibition of glycogenesis, Burke’s team compared a control diet of 7g/kg of high-GI carbs with two experimental treatments consisting of the control diet plus a substantial amount of added fat (1.6g/kg) and protein (1.2g/kg), and a matched-energy diet which was the control diet with added carbs to equal the calories of the experimental treatments.17 Subjects trained for 2 hours at 75% VO2max, ending off the session with four 30-second sprints. Despite a high fat intake in the experimental group, no differences in muscle glycogen content were seen 24 hours after training compared to the low-fat groups.

Along these same lines, Fox and colleagues observed no difference in glycogen replenishment 24 hours after glycogen-depleting exercise despite the addition of 55g in the post-exercise meal and also in the two meals following it.18 Think about it, 165g of additional fat did not prevent the resynthesis of identical amounts of glycogen the next day. And yes, carbohydrate content was the same in both diets. So, unless you’ve trained to depletion, and are going to train the exact same muscles in another exhaustive event within 24 hours, concerns of post-exercise fat getting in the way of glycogen resynthesis is just plain silly – especially if your total daily fat intake isn’t stupendously high to begin with.

Recently, an online forumite posed an interesting question – should omega-3 fatty acids be avoided post-exercise due to their anti-inflammatory properties which could potentially hinder protein synthesis? As a corollary, should arachidonic acid’s pro-inflammatory properties be taken advantage of at this time? While omega-3 fatty acids are anti-inflammatory, they’re also vaso-dilatory (increasing blood flow). Incidentally, they’re also broncho-dilatory (increasing breathing capacity). So, whatever detriment they might have near exercise is likely neutralized by other factors. As for arachidonic acid supplementation, a recent trial saw a decrease in the inflammatory effect of exercise.19 Although it increased anaerobic sprint capacity, it had no effect on maximal strength or body composition. Alan Aragon’s Research Review, January, 2008 – Inaugural Issue Page 4

Is It Necessary to "Spike" Insulin Post-workout?

Another concern of the fat-free-post-workout camp is the blunting of the insulin response. The rationale of maximizing the insulin response is to counteract the catabolic nature of the post-trained state, switching the hormonal milieu into an anabolic one, thus speeding recovery. Although this might benefit those who train fasted or semi-fasted, many don’t realize that a pre-exercise meal (and in some cases the mid-exercise meal) is doing more than enough spiking of insulin levels for anticatabolic purposes.
It’s an important objective to not only maximize muscle protein synthesis, but also minimize protein breakdown. However, the latter doesn’t require a massive insulin spike, but rather just a touch beyond basal/resting levels. To illustrate this, Rennie & colleagues found that even during a sustained high blood level of amino acids, no further inhibition of muscle protein breakdown occurred beyond insulin elevation to approximately 15 μU/l,20 which is slightly above normal basal levels of 5-10 μU/l.
To reiterate, the pre-exercise meal can have profound effects on insulin levels that surpass the length of the training bout. Tipton’s team found that as little as 6g essential amino acids + 35g sucrose taken immediately before exercise (45-50 minutes of resistance training) was enough to keep insulin elevated to roughly 4x above fasting levels 1-hour post-exercise.21 It took 2 hours post-exercise for insulin to return to resting levels. A similar insulin response was seen with 20g whey by itself taken immediately preworkout.22 If carbs were added to the pre-training protein, there would be yet a greater insulin response.

As far as solid food goes, Capaldo’s team examined various metabolic effects during a five hour period after ingesting a meal composed of 75g carb (47%), 37g prot (26%), and 17g fat (27%).23 Although this study didn’t examine training effects, this meal would make a nice post-workout meal due to its absolute (and proportional) amounts of protein and carbohydrate. The fat-fearing camp would warn against the meal’s fat content interfering with the insulin response. However, this meal was able to raise insulin 3 times above fasting levels within 30 minutes of consumption. At the 60 minute mark, insulin was 5 times greater than fasting. At the 300 minute mark, insulin levels were still double the fasting level.

Elliot and colleagues compared the effect of fat-free milk, whole milk, and a higher dose of fat-free milk (to match the calories of the whole milk) taken 60 minutes post-resistance exercise.24 Whole milk was superior for increasing net protein balance. Interestingly, the calorie-matched dose of fat free milk containing 14.5g protein, versus 8.0g in the whole milk (an 81% advantage), but still got beaten. The investigators speculated over the possible mechanisms behind the outcome (insulin response, blood flow, subject response differences, fat content improving nitrogen retention), but end up dismissing each one in favor of concluding that further research is necessary to see if extra fat calories ingested with an amino acid source will increase muscle protein synthesis. Lingering questions notwithstanding, post-workout milkfat was the factor that clinched the victory – at least in overnight-fasted subjects.

To put another nail in the coffin of the insulin spiking objective, post-exercise glycogen resynthesis is biphasic.25 Unlike the subsequent "slow" phase which can last several hours, the initial "rapid" phase of glycogenesis lasting 30-60 minutes immediately post-exercise is not dependent upon insulin. Maximizing post-workout hyperinsulinemia may be beneficial for athletes with more than a single exhaustive endurance-containing training bout separated by less than approximately 8 hours, but in all other cases, the benefit in "spiking" insulin is nil.

In line with this theme, interesting research has surfaced in recent years challenging the idea that highly glycemic (and thus insulinemic) carbohydrates taken post-workout are the optimal for recovery. Erith’s team found no difference between post-exercise high- and low-glycemic index (GI) carbohydrate intake on exercise performance the following day.26 In a similar study, Stevenson’s team actually saw better next-day performance in subjects who consumed low-GI post-exercise carbohydrate than those who consumed high-GI post-exercise carbohydrate.27

SUMMARY & APPLICATION

Hierarchy of importance, fat loading:

�� Of primary importance is total amount of the macronutrients by the end of the day. Timing of nutrients is secondary, since there’s typically a constant absorptive overlap between meals in a well-constructed diet.

�� Much of the existing sports nutrition research is done on endurance athletes, so an inevitable degree of extrapolation is necessary for those involved with non-endurance activities.

�� 2-6 days of high fat intake (~60-70% of total kcals) can result in "fat adaptation", a state increased fat oxidation during training, and in conditioned individuals, at rest as well.

�� Becoming "fat adapted" offers little to no ergogenic benefit. Adding a final-day-day carb load to a fat loading phase hasn’t proven to remedy its lack of performance effect.

�� Impaired sprinting ability resulting from fat loading carries negative implications for its utility in competitive endurance and ultra-endurance events, since they include intermittent bouts of increased intensity. Fat loading carries more risk than benefit, and can safely be avoided.
Single pre-loads

�� MCT preloads do not increase performance or decrease glycogen breakdown during training. The scant data on LCT preloads indicate the same lack of benefit.
During exercise

�� During exercise, MCT doesn’t enhance performance, and can cause gastrointestinal upset, decreasing performance. For these reasons, LCT and MCT can safely be nixed.
Post-exercise

�� Preliminary evidence suggests the potential for arachidonic
acid to enhance anaerobic capacity (sprints in particular). However, it had no effect on strength or body composition.

[ATZ]

Alan Aragon’s Research Review, January, 2008 – Inaugural Issue Page 5

�� High amounts of post-exercise fat (up to approximately 165g) do not reduce 24-hour glycogen synthesis. Thus, those who do not train the same muscles to glycogen depletion (or near-depletion) more than once a day shouldn’t be concerned with a normal fat intake, even in the post-workout period.
Is spiking insulin necessary post-workout? Generally not.

�� No greater inhibition of muscle protein breakdown has been seen beyond insulin elevation to approximately 15 μU/l, which is slightly above resting/basal levels of 5-10 μU/l.

�� In one study, whole milk was superior for increasing net protein balance post-workout, despite the calorie-matched dose of fat free milk containing 81% more protein.

�� The initial 30-60 minute "rapid" phase of glycogenesis immediately post-exercise is not dependent upon insulin.

�� There’s no need to attempt to spike insulin for recovery purposes since maximal effects are seen at minimal elevations. Simply getting enough total substrate surrounding the training bout suffices, at least within the context of a 24-hour separation between exhaustive training of the same muscles. Multiple depleting endurance-type bouts per day (i.e., < 8 hours between bouts) may be the exception to this rule.

�� On a related tangent, it’s been commonly recommended to maximize post-exercise hyperglycemia and hyperinsulinemia by consuming high-GI carbohydrates. However, this strategy has been seen to offer no benefit on next-day performance, and one recent study even saw endurance impairment.

REFERENCES
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From Alan Aragon’s Research Review, January, 2008 – Inaugural Issue Page 6