Since I started going to the gym a month

Put the calorie cut back this week, keep feeding on cue with a drink and a snack beside you, and let Wednesday's weight check plus the lactation visit settle the question — that combination, not the gym, is what will answer whether your milk is getting through.

One honest limit first: I don't have a card on exercise and milk supply, so I'm not going to give you a number or a verdict on the gym. What I can do is point at the levers that are yours tonight, and what the Wednesday check needs to settle. I can't diagnose your baby, and I don't change anything about your medicines or your baby's.

1) What you've tried vs. what I'd do instead

• Tried: cutting calories hard while exercising. Swap: reverse the cut for now — this is not the month to chase weight while you're feeding a 4-month-old. The variable to change this week is what you eat and drink, not whether you go to the gym.
• The official public advice I checked today (NHS, page last reviewed 15 May 2026) is that you don't need a special diet while breastfeeding, but you do eat a varied diet — protein foods like beans, pulses, fish, eggs, lean meat; dairy or fortified alternatives; starchy foods like rice, bread, potatoes; and you drink plenty of fluids, with a drink beside you when you settle to feed. That's the whole "eat enough" plan, and it's ordinary food, not a product.
• The thing that usually decides a baby's weight is how the milk gets *out*, not how much the mother eats in the abstract. So the Wednesday weight check and the lactation visit should be used for two specific asks: a test weight with the number written down and compared to the birth weight and the last weight, and one feed watched for latch and transfer. Those two answers are worth more than any week of guessing.
• Keep the exercise if you can hold the eating around it. If a session leaves you lightheaded, dizzy or shaking, that session is the problem — change it, don't change the baby.

2) Tonight and tomorrow — each step under 25 minutes

• Fill one large bottle or jug with water and put it where you feed. Refill it without thinking about it.
• Keep one "feed snack" within arm's reach of wherever the baby sleeps: bread with nut butter, a boiled egg, yoghurt, banana with nuts, cheese and crackers. No shopping, no new products.
• Put a real protein-and-starch plate in front of you at least twice a day, and eat it while someone else holds the baby if that is the only way it happens.
• Feed on cue rather than on a clock, and don't let a long stretch build up. Wake the baby for feeds if they are not asking.
• 10 minutes tonight: write down the last 24 hours — feed times, how long, left/right/both, and every wet nappy. Times are enough, no amounts.
• Handover sentence for whoever covers the school run or the evening, so it doesn't depend on your memory: *"Feeds are on cue — if he doesn't ask, wake him. Count wet nappies and write them down. If he won't feed, is floppy, is hot, or the nappies are much fewer, call me and if I'm not answering take him in."*

3) Avoid list

• Don't cut hard or skip meals and then train fasted.
• Don't judge your supply by how full your breasts feel, or by one bad feed — that's not a measurement.
• Don't start anything to "boost" milk — no powders, herbal blends, or anything bought online. If you're considering a supplement, ask your GP, health visitor or the lactation consultant; the same NHS page says vitamins are a conversation to have with them, and a vitamin D supplement in autumn and winter is a routine one to ask about.
• Keep caffeine modest while your baby is under 6 months — it passes through the milk and keeps babies restless.
• Don't change any medicine, yours or the baby's, on the back of this message. If you're the one feeling faint, dizzy or barely eating, that's your own doctor's appointment this week, not something to push through.

4) Red flags — when to stop doing this at home

Call your local emergency number and go in now if any of these appear: a temperature of 38 °C or above, or the baby feels hot or cold and isn't himself; hard to wake, limp or floppy, or only moves when handled; will not feed at all; fast or laboured breathing or blue lips; green vomit; blood in the stool; a fit; a sunken soft spot on the head; or markedly fewer wet nappies than usual. For a baby under 3 months with a fever, that is the emergency route, not a same-day call. Fewer than 4 wet nappies in 24 hours is one of the things a young-infant assessment asks about — write the count down rather than deciding at home.

Not an emergency, but don't let it slide: at Wednesday's visit, if the test weight hasn't moved or has dropped, or the feed still looks like poor transfer, ask for the same-day plan and what "back in a week" should look like before you leave the room.

5) Decision tree

• Is the baby feeding well, alert, with normal wet nappies and no fever? → Keep the Wednesday weight check and the lactation visit as booked, do steps 2 and 3, and review on the numbers.
• Alert but nappy counts are down or he's been unusually sleepy at feeds? → Same-day call to your paediatric service or health visitor, with your 24-hour log in hand. Don't wait for Wednesday.
• Any red flag in section 4? → Emergency route now, log and any packaging in your bag.

6) What "better" looks like in 24 hours

Not a fixed supply, and I'm not promising one. Concretely: you ate three meals with protein and something starchy, had a drink at every feed, exercised in a way that didn't leave you shaky, wrote down the 24-hour feed and nappy tally, and handed over the one sentence above. If the tally still looks normal tomorrow, you can go into Wednesday calmer and with the one number that actually matters — a test weight.

I don't diagnose, and I don't adjust anything about feeding or medicines on my own. The weight check Wednesday, with a feed watched, is the right door; this is just how to walk into it ready.