Is it normal to lose ~10 pounds in 4 months of casual swimming?

I started swimming a couple times a week about 4 months ago. I’ve also gone down from ~185 pounds to ~175 pounds.

My swimming routine is usually about 30 minutes and consists of 4 laps freestyle and 1 lap from the other strokes. Nothing else about my diet/exercise has changed during this time.

Not complaining but just wondering if I should be worried about something else. For context, I’m a 26 year old 6’1" male.

A couple years ago, I noticed some swollen lymph nodes in my neck, and they haven’t changed in size since then but they’re still there.

30 min and 4-8 casual laps a few times a week doesn’t seem like it should have much effect on your weight imo.

But also 10 lbs over 4 months isn’t that dramatic either. My body weight can fluctuate 5 lbs over the course of 1 day. If you think your casual swim is tipping the scales into some undesired weight loss, have yourself an extra snack!

You have probably lost a bit of fat and gained muscle. However, you should seek out a doctor for your nodes; it’s still better to know what it is exactly!

Flor said:
You have probably lost a bit of fat and gained muscle. However, you should seek out a doctor for your nodes; it’s still better to know what it is exactly!

Call me a cynic, but there is no way OP is gaining muscle from 250 yards twice a week. Unless he’s doing significant lifting on the side.

@Diya
If OP has gone from a completely sedentary lifestyle to regular exercise, then he’d be building muscle. That’s what happens when you increase exercise and don’t increase calories.

Alva said:
@Diya
If OP has gone from a completely sedentary lifestyle to regular exercise, then he’d be building muscle. That’s what happens when you increase exercise and don’t increase calories.

The amount of calories this amount of swimming is burning is negligible. They can’t be that out of shape as a 6’1" 26 yr old 185lb male.

I wouldn’t be really freaked out, but it’s worth a visit to your doctor.

@Ori
Swimming alone might not burn that much, but the fact is that OP was eating at maintenance, then began swimming, burning maybe 200 calories, putting him at a deficit. 5lb in 4 months is about 1000 cals/week. Plus, the routine of getting up and out to the pool will also help burn a little more.

@Diya
Forgot this information, thanks. Yeah, I kind of agree even though there’s still a chance if OP has a very sedentary lifestyle.

Get the doctor to check out Lymph nodes, esp if they don’t hurt. Former non-Hodgkin lymphoma survivor here.
Better to get checked. I was super anemic as well.

  1. Yes, that’s a reasonable amount to lose.

  2. Get those lymph nodes checked out anyway.

Rule 1: don’t ask strangers on the internet for medical advice.

Doesn’t matter if the weight loss is from swimming, get those lymph nodes checked regardless.

It really depends on what you were otherwise doing. If you add exercise, burn calories, and keep your diet consistent, you will lose weight. And swimming is one of the best calorie-burning exercises around!

Your calorie burn is going to be around. 30 min = 250-400cals(average ish 350) burn x 4 times x 16 weeks = 22400 calories. 10lbs of fat is 35000 calories. You probably didn’t burn more than 2/3 of that weight. Also, bloat/water weight will make your weight swing 4-5 lbs.

One pound of fat is roughly 3500 kcals, so 10 pounds is 35,000 kcals. If you’ve swum 35 times in these 4 months, that would be a calorie burn of a thousand calories for a 30-minute easy swimming session. This just isn’t plausible!

OTOH, if you ate 300 kcals less than you burned on every day of this 4-month period, that would also add up to roughly the same weight loss. Eating 300 kcals less than usual happens quite easily; it could be a dietary change you’ve not even noticed! Add to this that you might have a little less water and glycogen stored in your body right now than you had at your previous weigh-in, and the numbers start to make sense.

Definitely get those lymph nodes checked out, though!

So it’s more nuanced than this, but a pound of fat is roughly 3500 calories. To lose four pounds in 10 months, you would have to be in a daily deficit averaging about 300 calories. That’s extremely reasonable as swimming is very calorically demanding. Even if you are eating more or the same, that is very reasonable. I dunno about the lymph nodes though.

Bruv, go to the doctor.

It all depends on your body. I actually gained ~20 pounds in 6 months of swimming because I was underweight with very little muscle and had a low appetite before.

I’ve lost 2 stone swimming after 8 weeks & I started losing weight; people are asking where the belly went. I look a lot better! 5 days a week, 90 mins pool time. I stay swimming till the end of the session; love to swim & can swim a lot better. Even gone up the deep end & only started swimming regularly in June 2023. Had to tread water first before deep end just in case.

I had to change it to kgs, but 4 kgs in 4 months isn’t a dramatic loss and fits if you’ve increased physical activity.