I would assume feeling tired after eating is something common, since that always happened to me after lunch in high school, but it seems a bit strange now. Like today I bought a sandwich on my way to school and I ate it on the train but when I got off the train and started walking I was dead tired, almost to the point where I couldn't keep my balance. I started drinking the soda I had with the food after I got tired and it helped a bit.

Could the sugar or something have anything to do with it? Any advice?

It sounds very much like Diabetes, although I couldn't say for sure.  Have you ever been checked for Diabetes?

zanderlex : Its natural for that to happen. Your body is using energy to digest your food (also you blood sugar levels may have dropped a bit depednign on what you had in your sandwich.) hence why you are tired especially food with high sugar or high protein. I would try to stick away from drinking soda often and drink water as it does the opposite.

supernerd117 : I did fear that, but if it was that, wouldn’t I feel tired before I eat? Pretty sure I need to eat at specific times if I had that.
DylanMcCaig: I had a spicy Italian sandwhich from Subway. Didn’t actually have soda, I had that AFTER I ate and got tired to give me more energy.

zanderlex : I suppose it may depend on what you eat.  Like Dylan said, your body is using energy to digest food.  That may include sugar that you need.  I'm no expert, though; and I don't want you to panic or anything like that.  I'll also mention that I'm often tired after eating, but don't have Diabetes.  I'm overweight, and that's the main thing dealing with it imo.  I had a feeling you meant tired in a different way than what I experience, though.  I'm pretty much always tired  idk tho.  I don't suggest giving up Subway.  From what you've told me, it sounds like you like it a lot (me, too!).  I actually have a cousin with a bacon allergy that ate a lot of bacon on his birthday.  He LOVES the taste of bacon.  Anyhoo, I'll be praying for you, even if this is but a little thing.

supernerd117 : I read panic. Is that a viable option?

Yeah, it does look like insulin malfunction. My husband has a similar problem when he eats too many carbs too early on (shaking, sleepiness, etc.)

Try to find a pattern (if possible) about your energy crashes (what you eat, what you ate earlier, The time of The day). Then for sure, you need to talk to your doctor.

janus : What do you mean by early on? As in the morning? I really hope it just has something to do with eating that type of food so early in the day. Same thing happened Monday after eating the exact same sandwich. Though I'm not sure if I ate anything the other 2 days since then so I can't really compare them to anything.

zanderlex : so you drank after you ate (and I'm guessing you were already tired) and then drank soda. yeah that wouldn't help much. It gives you an initial burst of energy but you get a massive crash afterwards. happen to me whenever I drink fizzy drinks and energy drinks. The italian sandwich I don't know what is in it but some foods take longer to burn than others.

zanderlex : Yes, in The morning. He can eat sweets after 1 or 2 in The afternoon and is generally fine.

DylanMcKaig : I believe there might have been some pepperoni, and maybe some turkey in it, but I'm not exactly sure.

zanderlex : Turkey takes a long time to burn so that will be why you are tired.

DylanMcCaig: If that's the reason, then I will be relieved, but I'm not sure if that's really what was in it, but I'll make sure to ask them what's in it the next time I go there.

I sometimes have this problem as well, but not often. It most commonly happens to me after eating sugary food. Sugar is supposed to make you feel more energetic for a while but it just makes me go straight to tired. So when I have trouble getting to sleep I can have ice cream and fall asleep right afterward

You may have been short changing yourself on sleep. If you do not get at least 4-5 hours sleep a night,you do throw off your system and you do wind up sluggish. Caffeine is a magician,it can make you feel energetic,but at a cost,you crash pretty hard when it burns off.

Oldschool777 : The caffine never caused me to crash, once I had it, the tiredness goes away for the entire day, its all from the food.

Well,eating a lot at one time would cause that. I know when I used to eat Monster Burgers (you might want to avoid them if you are watching calories,I believe they are around 1500 calories.) I would conk out a few hours later,due to me stuffing myself.

Oldschool777 : That probably wouldn't be it later, this doesn't happen hours later but like 20 to 30 minutes after I finish eating it.

this is actually pretty common for 2 reasons...

1. The main reason already explained is that once you finish eating your body puts energy (blood flow) into digesting the food. Generally that starts ramping up 30 minutes after you're done eating. Depending on the quantity of food it can be quite a drastic decrease in energy.

2. You're probably done puberty at this point. Now that you're 21 you are for sure out of puberty (lasts for most guys until 18 or 19) which will have an effect on metabolism and energy levels. You might have to make adjustments for what you eat, how much you eat, and when you eat. This is something that happens to everyone post puberty but sometimes it affects certain people more than others. This is just a guess though.

My guess might be the quantity of food if you had a footlong sandwich. That's a lot of food to eat at one meal. Especially being post puberty now so your need for calories should have dropped off.

This is normal. I just woke up a bit ago and ate some chicken spagatii and garlic bread and I have a tired feeling. I get tired alot after I eat... as do alot of other people. It's nothing to worry about