Every source seems to give a different number. One article says “eat for two.” Another gives you a trimester-by-trimester chart that reads like a lab report. Neither one is actually that helpful when you’re standing in your kitchen trying to figure out what to eat tonight. Here’s the honest, short version: the extra calories you need during pregnancy are smaller than most people expect — roughly 300 to 340 extra calories a day in the second trimester, and 350 to 500 extra in the third. Breastfeeding asks for more: typically 400 to 500 extra calories a day if you’re exclusively breastfeeding.
Every one of those numbers is an addition to your pre-pregnancy TDEE, not a fixed number that applies to every woman. If you want to understand your own baseline before adding anything to it, the TDEE calculator is useful here — not as a weight-loss tool during pregnancy, but as a way to understand what your body was already running on before pregnancy increased the demand. One important note before we go further: any significant changes to your diet during pregnancy or breastfeeding should be discussed with a midwife, GP, or registered dietitian. This article is here to give you educational context, not a clinical prescription.
How TDEE Changes During Pregnancy — Trimester by Trimester
First Trimester — Minimal Extra Calorie Needs
This one surprises a lot of people: no additional calories are needed in the first trimester. The embryo’s energy requirements at this stage are tiny, and the nausea and food aversions that show up for many women in weeks 1 to 12 often naturally bring intake down anyway. The American College of Obstetricians and Gynecologists (ACOG) confirms this directly — for women with a healthy pre-pregnancy weight, there’s no extra calorie requirement in this stage.
Second Trimester — An Extra 300–340 Calories Per Day
From around week 13 to week 26, most guidelines suggest adding roughly 300 to 340 calories a day above your pre-pregnancy TDEE. This reflects the real, measurable costs of this stage — fetal growth, placental tissue, expanding blood volume, and growing uterine and breast tissue all draw on energy. In practical terms, 300 calories is a moderate snack, not a meal — something like 150g Greek yoghurt, a banana, and a small handful of nuts covers it easily.
Third Trimester — An Extra 350–500 Calories Per Day
Weeks 27 to 40 carry the highest fetal growth rate of the entire pregnancy, and the energy cost of simply maintaining the pregnancy — increased cardiac output, higher respiratory demand, and the fat stores your body builds in preparation for breastfeeding — peaks here too. Most guidance puts the addition at 450 calories, with the higher end of the range (closer to 500) more relevant for women who were underweight before pregnancy, or who are carrying multiples.
Why Different Health Authorities Give Slightly Different Numbers
Here’s the honesty most articles skip: ACOG and the NHS don’t give identical figures. ACOG generally recommends around 340 extra calories in the second trimester and 450 in the third. The NHS takes a more conservative position — no extra calories are needed until the third trimester, and even then it suggests around 200 extra calories a day, not 450. Neither is “wrong.” They reflect different national guidelines and slightly different assumptions about baseline diets and activity levels. The practical takeaway is to treat these as a reasonable range rather than a single hard target, and to let your midwife or GP fine-tune the number based on your specific situation.
Calorie Needs During Breastfeeding
How Many Calories Does Breastfeeding Burn?
Producing breast milk costs the body approximately 500 calories a day for exclusive breastfeeding. Some of that — typically 100 to 150 calories — can come from fat stores your body laid down during pregnancy specifically for this purpose, which means your net additional dietary need usually sits closer to 350 to 500 calories above your pre-pregnancy TDEE. A detailed nutrition review published through the National Institutes of Health backs this estimate, calculating it from the average daily milk volume produced and the energy content of that milk. For women who were overweight or obese before pregnancy, the postpartum fat mobilisation effect tends to be larger, so the net additional dietary need may sit at the lower end — 300 to 400 calories a day — but total intake generally shouldn’t drop below 1,800 calories without clinical guidance, since inadequate intake can reduce milk supply.
Is It Safe to Lose Weight While Breastfeeding?
Modest, gradual weight loss — generally no more than 0.5 kg a week — is considered safe during breastfeeding by major clinical guidelines, and doesn’t appear to affect milk composition or supply when total calorie intake stays adequate. What isn’t recommended is aggressive restriction — more than 500 calories a day below your breastfeeding TDEE — since this can reduce milk supply and affect the nutritional quality of your milk. A sensible approach many midwives suggest: eat at your breastfeeding TDEE for the first 6 to 8 weeks postpartum, then talk to your midwife or GP about whether a modest, gradual deficit makes sense for you. Our calorie deficit guide explains how a gentle deficit works generally — useful background once your provider has confirmed it’s appropriate for your situation.
Signs Your Calorie Intake May Be Too Low While Breastfeeding
A few signals worth flagging to your midwife or GP rather than waiting out: a noticeable drop in milk supply, ongoing fatigue that doesn’t improve with rest, dizziness, or a baby who seems unsatisfied after regular feeds. None of these automatically mean low calorie intake — there are several possible causes — but they’re worth raising rather than assuming will resolve on their own.
Nutritional Priorities During Pregnancy and Breastfeeding
Protein — Higher Needs Throughout
Protein needs increase to roughly 1.1g per kilogram of body weight a day during pregnancy, and breastfeeding generally calls for an additional 25g a day above your normal baseline. This supports fetal tissue development, placenta and amniotic fluid production, and the protein content of breast milk. For a 65kg woman, that works out to roughly 70 to 85g of protein a day — entirely achievable through a standard mixed diet of eggs, dahi, chicken, daal, and paneer, without needing specialised supplements. If you want a general sense of protein needs as a baseline before adding the pregnancy increase, our protein per day guide covers the standard adult calculation.
Key Micronutrients Beyond Calories
This isn’t a full micronutrient guide — just the four that matter most clinically:
- Folate (folic acid): critical in the first trimester. The NHS recommends a 400 microgram daily supplement, taken in addition to dietary sources, through the first 12 weeks of pregnancy.
- Iron: requirements rise substantially during pregnancy to support increased blood volume — found in daal, red meat, and fortified foods, with supplementation if your provider recommends it.
- Calcium: essential for fetal bone development — dairy and calcium-fortified foods are the main dietary sources.
- Vitamin D: a 10 microgram daily supplement is recommended throughout pregnancy and breastfeeding in the UK. This is worth particular attention for South Asian women, since darker skin tones and lower sun exposure in northern climates are both linked to lower baseline vitamin D levels.
Supplementation decisions should always be made with a healthcare provider — this section is here to build awareness, not to replace that conversation.
A Quick Reference — Extra Calories by Stage
| Stage | Extra Calories (above pre-pregnancy TDEE) |
|---|---|
| First trimester | None typically needed |
| Second trimester | ~300–340 cal/day |
| Third trimester | ~350–500 cal/day |
| Exclusive breastfeeding | ~350–500 cal/day |
Frequently Asked Questions
How many extra calories do I need when pregnant?
None typically in the first trimester, roughly 300 to 340 extra a day in the second, and 350 to 500 extra a day in the third — all added to your pre-pregnancy TDEE, not a fixed universal number.
How many calories should I eat while breastfeeding to lose weight?
Most clinical guidance suggests eating at your full breastfeeding TDEE for the first 6 to 8 weeks postpartum, then discussing a modest deficit (no more than 500 calories below that TDEE) with your midwife or GP if weight loss is a goal. Going lower risks reducing milk supply.
Should I eat more if I’m breastfeeding twins?
Likely yes, but this needs individual assessment from your midwife or GP rather than a generic number — milk volume needs for twins vary considerably and should be guided by your baby’s growth and feeding patterns, not a blanket calorie figure.
Is it okay if I’m not very hungry during the first trimester?
Yes, this is common and expected. Reduced appetite alongside nausea is normal in the first trimester, and your calorie needs at this stage are minimal anyway. If you’re struggling to keep food down consistently or you’re losing significant weight, mention it to your midwife.
Can I use a TDEE calculator during pregnancy?
Yes, as a way to understand your pre-pregnancy baseline before adding the trimester-specific calories covered in this article. It isn’t designed or intended as a weight-loss tool during pregnancy — its value here is purely in establishing the starting number you’re adding to.