Formula weight gain isn't a simple comparison — here's what actually matters
Every new parent asks this at some point. You're scrolling through supermarket shelves or pharmacy aisles and you notice two almost identical-looking boxes, and somehow you end up trying to reverse-engineer whether one will make your baby heavier than the other. It's a normal question. The answer, though, is a lot less straightforward than a brand name.
qual fórmula engorda mais nan ou aptamil — the short answer that most people don't like
Neither one is designed to make babies gain more weight. Both are governed by strict EU and international nutritional standards that specify exactly how much protein, fat, carbohydrate, and calories each stage must contain. The difference between a tin of Nan and a tin of Aptamil is marginal at best, and in most cases, statistically invisible when it comes to weight gain outcomes. If you're looking at the ingredient labels side by side, you'll see very similar macronutrient profiles. Both use a blend of vegetable oils for fat. Both include lactose as the primary carbohydrate in Stage 1. Both fortify with iron, vitamins, and in many variants, HMOs (human milk oligosaccharides) or GOS/FOS prebiotic blends. The caloric density of both is approximately 67 kcal per 100 ml of prepared formula — that's not a coincidence, it's a regulatory baseline.
What actually drives weight gain on formula
The single biggest factor isn't the brand. It's the volume your baby consumes and how their individual metabolism processes it. I've seen two babies on the exact same formula, same preparation method, same feeding schedule, and one gaining well while the other barely does. That's not the formula — that's genetics, growth curve trajectory, and sometimes underlying issues like reflux or a mild intolerance that manifests differently in each child. The second biggest factor is preparation accuracy. If you're scooping with a heaped scoop, or adding slightly less water than the instructions say, you're creating a more calorie-dense feed without realizing it. That's how some babies appear to "gain faster" on one formula — they're just getting more calories per millilitre because the mix is slightly concentrated. Conversely, over-diluting makes the formula less caloric and can actually slow weight gain. This is one of those things that nobody talks about enough, and it accounts for a surprising amount of the variation parents notice between brands.
A closer look at Nan and Aptamil specifically
Nan (Nestlé) and Aptamil (Danone) are both premium mainstream formulas with very similar Stage 1 and Stage 2 product lines. Let me walk through what distinguishes them in practice. Nan Optipro, which is one of the more common variants, emphasizes its protein profile — it uses partially hydrolysed whey protein, meaning the protein is pre-broken down into smaller chains for easier digestion. The fat blend typically includes palm olein, which some parents and pediatricians have opinions about. Palm olein can bind with calcium and form insoluble soaps in the gut, potentially leading to firmer stools. This doesn't affect weight gain directly, but it can affect how comfortably a baby passes stool, and constipation stress can indirectly influence feeding behaviour.
Aptamil Premium or Aptamil Profutura takes a different approach to the fat blend. It generally uses a palm oil–free formulation, substituting with sunflower oil to reduce the soap-forming reaction I just described. It also includes a GOS/FOS prebiotic fibre blend at a specific ratio (0.8:1 in many markets) and, in newer variants, 2'-FL HMOs. The protein structure in Aptamil tends to be less hydrolysed than Nan Optipro, meaning it's closer to intact whey protein. Neither advantage translates into a meaningful weight gain difference. What it does translate into is digestive comfort for some babies. A baby who gets fewer hard stools and less straining may feed more willingly and consistently, and that consistency is what actually moves the needle on weight.
The counter-intuitive part most parents miss
More protein in formula doesn't mean more healthy weight gain. In fact, several large cohort studies have found that higher protein content in infant formula is associated with faster weight gain in the first year, but also with a slightly higher risk of overweight in later childhood. The WHO and European paediatric nutrition guidelines explicitly recommended reducing formula protein levels in the 2010s for exactly this reason. So if you're looking for a formula with "more" protein thinking it will help a underweight baby, you're actually working against the current scientific consensus. The other thing parents routinely misunderstand is the concept of "comfort" or "AR" (anti-reflux) formulas. These are thicker, usually with added starch or rice flour. They don't make babies gain more fat or muscle — they just sit heavier in the stomach and may reduce spit-up. A baby who spits up less may retain more of what they've consumed, which shows up on the scale, but that's retention, not enhanced nutrition.
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My own experience with this question
I went through this exact comparison with my own child a few years ago. We started on a standard cow's milk formula, the baby was gaining adequately but had quite firm, dark stools and seemed uncomfortable during bowel movements. We switched to Aptamil palm-oil-free variant on the suggestion of our paediatric nurse. The stool softness improved noticeably within three to four days. Weight gain continued on the same trajectory — it didn't accelerate, didn't slow down. What changed was feeding behaviour. The baby was happier after feeds, slept better, and didn't associate eating with discomfort. That's the real win, and it's invisible if you're only tracking grams on the scale. The flip side is equally worth noting. A friend of mine switched her baby from Aptamil to Nan Optipro because she'd read somewhere that the hydrolysed protein would be "easier to digest." Her baby developed worse gas and more frequent loose stools on Nan. The protein was pre-broken down, yes, but the overall composition — different fat blend, different prebiotic profile, different mineral balance — interacted with her baby's gut microbiome in an unexpected way. There's no universal right answer here.
When to actually worry about weight gain
If your baby is consistently falling off their growth curve — dropping percentile bands on the WHO growth chart — the formula brand is almost never the primary issue. At that point, you need to look at feeding frequency, total daily volume, absorption issues, thyroid function, and a handful of other clinical variables. No commercial formula brand is going to solve a medical growth problem, and switching between Nan and Aptamil won't move the curve if there's an underlying issue. Conversely, if your baby is gaining well on one formula and you switch them to another out of curiosity, you might see a small fluctuation of a few hundred grams over a couple of weeks. That's normal biological variance, not a formula effect. Growth charts smooth out over months, not days.
A practical decision framework
Instead of asking which formula makes babies gain more weight, ask these questions: Is my baby gaining along their percentile curve? If yes, the formula is fine. Stop worrying about the brand.
Is my baby having digestive discomfort — hard stools, frequent spit-up, apparent gas pain? Then the fat blend and prebiotic profile matter more than caloric density. In that case, a palm-oil-free formula with GOS/FOS (Aptamil's strength) or a partially hydrolysed protein formula (Nan Optipro's strength) might be worth trialling for two weeks while monitoring stool pattern and feeding comfort. Is your baby underweight and not gaining adequately despite full feeds? Then you need a paediatrician, not a different formula box. There are specialist energy-fortified formulas and pre-thickened formulas that are genuinely different from standard Nan and Aptamil, but those are medical products that require professional guidance.
The bottom line
The difference in weight gain between Nan and Aptamil is negligible for the vast majority of babies. Both meet the same nutritional standards. Both provide approximately the same calories per millilitre. Both support healthy growth when fed correctly. The factors that actually move the weight needle are feeding volume, preparation accuracy, your baby's individual metabolism, and digestive comfort — none of which are determined by which brand you buy. If I had to pick one based on my own experience and what I've observed with families I know, Aptamil's palm-oil-free approach and prebiotic blend gives a slight edge in digestive comfort for some babies, and comfort translates into better feeding consistency. But that's a soft advantage, not a weight-gain advantage. And it doesn't apply to every single baby — my friend's experience above is proof of that.
So qual fórmula engorda mais nan ou aptamil — honestly, neither one, not in any meaningful or consistent way. Pick the one your baby tolerates better, prepare it correctly, and trust the growth chart over the marketing on the box.
