Fat Babies are Smart Babies, Study Says

The prevailing attitude towards newborns’ weight gain in the first month of life is that greater weight gain is negatively linked with cardiovascular health down the line. Rapid weight gain in the first month of life can be indicators of obesity and diabetes down the road, as well.

However, a new study is showing that babies who gained 40 percent of their birth weight during the first four weeks of their lives had an IQ of 1.5 points higher by the time they were 6 years old when compared to their lighter peers who only put on 15 percent of their birth weight that first month.

This study came from a team of Australian and Canadian researchers who followed 14,000 babies from birth until they were 6 years old. All of the babies were in Belarus, and all were healthy according to the study.

According to Dr. Lisa Smithers, a postdoctoral fellow at the University of Adelaide and the one in charge of this study, the findings of this research are not surprising:

Other pieces of the literature pointed to this kind of effect, but nobody’s really also looked at that really early period, those first four weeks of life… This was additional to that other research which says growth in the first year [is important]; well, actually what we’ve shown is growth in those first four weeks is also very, very important.

This by no means shows that parents should force-feed their children as soon as they are born to be sure that they gain 40 percent of their birth weight. In fact, Dr. Beverly Muhlhausler – also from the University of Adelaide – is asking that more research be done in order to find out just how much weight is healthy for a baby of that age. She says, “It may be growing a bit faster is associated with higher IQ later on, but may also be associated with an increased risk of metabolic disease… Considering which one of those is more or less desirable is very difficult. So I think there’s probably still too early to go out and make any recommendations in terms of changing the growth profile we are currently recommending.”

While it might be too early to decide how much weight a baby should gain and what weight gain has to do with a baby’s health or IQ, these findings are incredibly interesting. The idea that a baby’s first four weeks of life can be important enough to determine IQ or patterns of behavior that might lead to other issues later in life isn’t entirely new, but this is one of the first studies to prove it.


Photo Credit: Bridget Coila


Mark Bill
Past Member about a year ago

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Jose L.
Jose L.2 years ago


If we were talking about 10 points or more, I'd pay attention, but making a fuss over such a small amount is like indulging in a number fetish. I think the main take is that there probably isn't any difference, and there are many things to worry about than to over-feed on the first month for the sake of reaching that 40% value.

PS: How do things shape if we look at 20% or 80% as the cut-off? Is 40% the ideal crossover point? Is there a bound that is ideal rather than 40 and above (eg, between 28.6% and 54.9% as "ideal").

PPS: What about 2 months out? What about 3 months out? Etc. What is the ideal weight for those time periods? Should we feed to 45.66% the first month, then slow down the rate by 15.6% for the second month. Increase it by 3.5% for the 3rd month?

PPPS: If we were to compute the month by month and all sorts of other detailed "idealities", does it all change if the kids were no longer born in Belarus, or if they were born in a different decade, or in a different hemisphere, or once the CO2 levels in the atmosphere surpass 400ppm average for the year???

Jose L.
Jose L.2 years ago

GGmaSheila D, some of these variables might be accounted for (subgrouped and weighted accordingly (no pun intended) or something like that), but some things likely have been missed and could make a difference to the end conclusion. For example, all were "healthy", but how did they define that? Might it include kids of a fairly low weight who otherwise did not get ill (hence were deemed "healthy") and weren't too far off the averages? If so, then those kids near the bottom would contribute to the (slightly) lower IQ group. But it would make sense if at an early age you are of fairly low weight that you might develop just a little slower. Get off to a slower start and so on average be a little behind by age of 6. Of course, you might be as capable as anyone else and that is why you qualified as "healthy" over that time period despite getting off to a slower start. So my point is that perhaps everyone is about the same, except the very low weight kids, and these bring down the average for the below 40% group.

Kathy P, if you had another kid, do you think you would put the same care? I suspect not. But even if you did, in general, I think that a heavier body would correlate with a lot of attention from the parents (mother, at least) more times than not.

Anyway, there are numerous possibilities, too many, to attribute much meaning in a measly 1.5 points on an IQ test (where 100 is the average).


If we were talking about 10 points or more, I'd pay attention, but mak

Kathy Perez
Kathy Johnson2 years ago

my son was 9'6'' at birth (I was only 104lbs when i became pregnant, so he seemed huge to me) he gained. a lot. He was a happy child from the get go, easy, slept through the night by the end of the first week, always alert, never cried. He was 24 lbs by the time he was 3 months old, he was also tall, a chunk. He is very bright. He is 3 now, knows his letters (and their sounds) number through 20, shapes through octagon, 10 colors, and he has always done everything early. He crawled at 4 months, walked at 7, spoke in sentences 4 words+ at 13 months. He is still bigger, 40 inches tall, 38 lbs (in the 80th percentile for both). We are very careful about what he eats. He never even tasted sugar until he was well over a yearold (his bday cake was his first sweet) and we eat organic. Hes just ahead.

GGma Sheila D.
GGmaSheila D.2 years ago

Interesting study but would like to know if weight gain and IQ were the only two parameters tested. What about birth order, parental IQ, any siblings/not, time spent with baby? There are so many variables in the kind of study done that I wouldn't necessarily get excited over this.


General good quality, loving care and feeding is all that a baby needs. I really don't see the need to be wasting tax payers money on this research. All babies and children differ, in body weight and IQ, it has nothing to do with weight, only love and care brings out the best in children as they age.

Jane R.
Jane R.3 years ago

Some Care2 members are funny (strange). I received a star from N.P. and sent one in return. I was going to say thank-you through an introduction as that's the only way I'm able to correspond, but to my surprise found out that she has me blocked! Strange since I've never had contact with her.
Everyone out there, have a wonderful day!

Phillipa W.
Phillipa W.3 years ago

I think it has more to do with being breastfed on demand and on cue than their actual weight.

Danuta Watola
Danuta Watola3 years ago

Thanks for posting.

Jane R.
Jane R.3 years ago

The heavier babies might develop higher IQ's because their parents spend more time with them as babies and toddlers. Weight alone can't have anything to do with it.