Let's make this clear and net.
First of all you can also avoid eating just after a workout if you're not hungry ( it's relly common ); just wait an hour or two maybe and then eat, unless you have a second workout later on the same day.
Your body is actually using the energy from pervious meals to replenish what you have used ( mostly in terms of glycogen ) during your workout. This is called an excessive post-exercise oxygen consumption. The slow component of this phenomenon happens in actually about 1h after you train ( mostly at high intesities ). Your body is actually consuming more oxygen than normal resting condition and relying mostly on the oxidative type of energy. This untill your energy stores are replenished.
And this is crucial for one reason: you have to replenish your energy levels first and then starting the adaptation cycle in terms of protein synthesis.
Protein synthesis is an extremely expansive process that tends to not occur when you have low energy levels, due to some molecular signals.
Now that I set this straight, we shall proceed with nutritional advices.
First of all I want to quote the most comprehensive review of litterature on the subject ( at the best of my knowledge ) in regards to the topic.
Determinants of post-exercise glycogen synthesis during short-term recovery.
This is an article published on Sport Medicine, so I don't know if you have full access ( if you don't, you can request the article here ); I will try to quote the highligts of the article referring to your questions:
[...] it is interesting to note that recently it was
shown that whole body and leg protein synthesis, as
well as net protein deposition, is enhanced when
nutrients are consumed immediately after exercise
as opposed to 3 hours later. These data and those
of Ivy et al. indicate that the timing of post
exercise nutrient intake may affect the rate of mus
cle glycogen synthesis, as well the rate of whole
body and leg protein synthesis.
Thus, it can be concluded that athletes should
consume CHO immediately after strenuous exercise
as this may increase the rate of muscle glycogen
Recently, we investigated
whether the addition of an insulinotropic protein
amino acid mixture to a larger amount of CHO
(1.2g/kg/h) would further increase muscle glycogen
synthesis rates. This study demonstrated that
when the total CHO intake is very high (1.2 g/kg/h),
the presence of a protein-amino acid mixture does
not further increase the rate of muscle glycogen
synthesis, despite a much higher insulin response.
The results of this study, and those of
others,[17,94] suggest that insulin is not the limiting
factor for muscle glycogen synthesis when total
CHO intake is high (1.0–1.2 g/kg/h). The availabili
ty of CHO post-exercise, on the other hand, seems to
play a more important role when maximal rates of
muscle glycogen synthesis are required.
It should be
noted that although protein and/or amino acid inges
tion may not always have an effect on muscle glyco
gen synthesis, there is evidence that amino acid
ingestion in combination with, and without,
CHO may increase post-exercise protein synthe
sis and net muscle protein balance (protein synthesis
minus protein degradation). Furthermore, studies
have shown that an increase in insulin levels when
plasma amino acid concentrations are high may
further increase net protein balance.[111,112]
However, the data clearly indicate high muscle
glycogen synthesis rates during the initial hours
after exercise can occur when a high-GI CHO diet is
ingested. (High glycemic index)
On top of that there are several other factors that the article covers ( but not in line with strictly what you ask ), that I'm not going to quote here but you can find in the article and are:
- Training status
- Feeding schedule
- Magnitude of muscle glycogen depletion
- Muscle fibers type
- Mode of exercise
I really advice you to get this paper and read it. It's not complicated, and in my honest opinion is the best aviable right now.