I’m about three weeks in to keto and for the last week or so I’ve been having Dymatize iso100 Gourmet Chocolate for breakfast at 7am as a blended iced coffee with 4 oz espresso and 2 oz heavy cream.
Before keto I drank just the espresso and milk or cream with lots of sugar and I felt energized and “raring to go”. I wouldn’t normally eat anything else for breakfast until an hour or two later when I settled in at work. I had hunger pangs but no energy drops.
Since I started adding the Dymatize to my coffee and removed sugar I have felt lethargic and worn down before that first meal about 9am. Almost like someone were pushing down on my shoulders with a lead weight.
Anyone else notice Dymatize or other protein shakes for breakfast “weighing you down”? (At 330# it’s not like I don’t have enough weighing me down already!) 
History (optional):
I can’t stand the taste of black coffee but the espresso gets me up and awake in the morning and I’m Cuban so I have to have my cafecito, it’s a way of life for Cubans. It’s like asking someone to give up their religion. Actually, it’s like asking a Cuban to give up rice & beans, which I’ve done to stay under 20 net carbs, so don’t ask me to give up any more!!! 
Before keto, and for about 20 years before that, I took one to two tablespoons of sugar in 4 oz of espresso plus 4 oz of milk. The first two weeks of keto I was experimenting with sweeteners. I tried erythratol/stevia liquid; Swerve powder; and then back to 1/2 tsp sugar with just my 4 oz espresso and 2 or 4 oz milk/cream. I didn’t like the taste of the erythratol or the Swerve, and I didn’t like the taste of coffee with “only” 1/2 tsp sugar, but with the 1/2 tsp tasted better than the fake taste of the E/S and the Swerve.
Then I thought to try a protein shake with my coffee to make it taste better. It worked! The Dymatize with coffee and cream tastes like a great chocolate shake and it has helped to get the coffee down, but at the same time my post coffee energy has gone the other way. Instead of perking up and feeling energized now I feel worn down, exhausted, and like I’m moving through mole asses. Yes, I said it, mole ASSES. 