T Nation

Feel Less Energetic After Breakfast Smoothie


I often have a breakfast smoothie in the morning (not perfect, but convenient and it gets some nutrients in me), but I sometimes notice an energy dip after having it, which especially affects concentration at work. This also occurs (to a slightly lesser degree) if I have milk/Carnation instant breakfast as well for a quick breakfast. Is there a nutritional mechanism that causes this?

Smoothie is:
1 banana
1 yogurt (either Liberte which is pretty sugary, or Activia greek flavored yogurt)
4 ice cubes


Throw in a TB of peanut butter and report back.


It is nutritionally based.

Banana is around 27g carbs (mostly fructose), negligible fat/protein. Yogurt is maybe another 20g carbs (sugar, lactose), maybe 8g protein?

So you’re having around 47 g carb (mostly fructose and glucose) and 8 g protein for breakfast. No fat, no fiber.

The physiological result is increased serotonin levels which makes you sleepy. Due to the source of carbs, your blood glucose spikes but quickly goes back to zero.

You need to consume more protein and fats and limit the carbs. Some kind of meat/eggs and some kind of nut butter or normal butter. This is what will boost dopamine and acetylcholine, which are essential for motivation and focus. If you do have carbs, they need to be mostly fiber to sustain your blood glucose levels.


small steak, 2 eggs, spinach

unflavored greek yogurt with almonds in it


Thank you both for the info and suggestions.

Tried 1 TB of peanut butter in smoothie this morning as suggested by tsantos, felt somewhat better. Still a little dip in energy, but a bit better and had better concentration. Would it be the added protein that makes the difference, or having a better balance between protein/fat/carbs, etc.? Other suggested adjustments are welcome as the smoothie is convenient and does taste good.

Seinix, thank you for this explanation. This makes sense - is there a broad guide which explains the rationale of how food affects energy/concentration levels (as well as managing risk for things like heart disease/diabetes)? I have seen things here and there and a few very good guides on this site that are particularly great for overall health and post-workout nutrition, but I haven’t found a guide that explains cause/effect of individual meals for daily energy/concentration and neurotransmitter explanations as you mention here.