Spoon-feeding link to child obesity 'not proven'

"Spoon-fed babies more likely to be overweight," reports The Independent. The study the news comes from found an association between feeding techniques and weight gain, although many other factors may also be involved.

The study looked at whether the way mothers introduced solid foods to their babies (weaning) was linked to the child's weight and their "eating style" as a toddler. Researchers looked at two methods of weaning: "traditional" spoon-feeding and what is termed baby-led weaning (BLW), where babies pick up food and feed themselves.

The study found that the BLW babies were less likely to be overweight when assessed between the ages of 18 and 24 months. However, babies in both groups were predominantly of a normal weight.

The researchers speculate that the BLW approach may lead to better appetite control in later life, but this speculation remains entirely hypothetical. However, they did find a bigger "satiety response" in the BLW group, which is the child's ability to regulate what they eat when they feel full.

The study does not show that spoon-feeding causes obesity. It has several limitations, including the fact that it is based on mothers self-reporting, which might affect its reliability. A longer follow-up period would also be useful, as it is currently unclear whether toddlers who were overweight would stay that way in the future.

Still, parental approaches to feeding are an important area of research. Experts agree that a relaxed attitude to feeding and allowing babies to explore food is best for the child, although this is often easier said than done.

Where did the story come from?

The study was carried out by researchers from Swansea University. There is no information about external funding. It was published in the peer-reviewed journal Pediatric Obesity.

This study was covered rather too uncritically in both The Independent and the Daily Mail.

The Independent reports on the study as if the researchers' hypothesis that baby-led weaning leads to better appetite control in later life is a proven fact. This is certainly not the case.

What kind of research was this?

This was a cohort study looking at whether the way babies were weaned was linked to their eating behaviour and weight at 18-24 months.

This type of study is often used to examine whether certain lifestyle factors are linked to later health outcomes, but it cannot prove cause and effect.

It is always possible that other factors (confounders) may influence the results of a cohort study, although researchers usually try to take these factors into account.

A lot of supportive evidence is needed before we can be reasonably certain that a lifestyle habit or exposure directly causes a health outcome. Ideally, as the researchers point out, a randomised controlled trial would be carried out.

The researchers say it is important to understand the role of the early feeding environment in determining the risk of obesity. For example, a "controlling parental child feeding style" has been associated with poorer appetite regulation in previous studies, such as a BMJ study covered by Behind the Headlines in 2012.

The researchers point out that traditionally infants are weaned with puréed foods, which tend to be spoon-fed by a parent or carer, alongside a gradual introduction to finger foods (standard weaning, or SW).

However, baby-led weaning (BLW) is a recent popular trend that emphasizes self-feeding by infants from the age of six months. This means foods are presented to the baby in their whole form and the baby decides which food item to select, how much to eat and how quickly to eat it.

The researchers set out to examine whether infants weaned using a baby-led approach exhibited differences in eating behaviour during their second year, compared with those weaned using a standard approach. The study also explored the role of maternal control, breastfeeding duration and the timing of the introduction of solid foods.

This is the second phase of a two-part study. The researchers say that in phase one, they showed that a BLW style was associated with "significantly lower levels of control" compared with standard weaning.

What did the research involve?

In phase one of the study, 604 mothers with an infant aged 6-12 months who had started consuming solid foods completed a questionnaire examining their weaning style.

The mothers were recruited through mother and baby groups in Wales as well as online parenting forums. They were classed as either baby-led or standard weaners:

• mothers were classed as baby-led weaners (BLW) if they reported using both spoon-feeding and purées 10% of the time or less
• mothers who reported using both spoon-feeding and purées more than 10% of the time were classified as standard weaners (SW)

The mothers also completed a standard child feeding questionnaire on breastfeeding duration and the timing of introduction to solid foods.

They were invited to take part in phase two of the study when their children were aged between 18 and 24 months. Three hundred and twenty five mothers responded to the invitation. After exclusion criteria such as child health problems or an incomplete survey were applied, 298 mothers – just under half the original sample – remained in the study.

These mothers completed a second child feeding questionnaire, answering questions about pressure to eat, monitoring, concern for child weight and perceived responsibility.

In particular, they were asked about:

• food responsiveness – desire of the child to eat in response to food stimuli, regardless of how hungry they are
• enjoyment of food – a positive eating style and enjoyment of eating
• satiety responsiveness – the child's ability to regulate intake of food in relation to feelings of fullness
• slowness in eating – the speed at which a child eats 
• food fussiness – where a child is "picky" and has limited food choices in terms of the range she or he will eat

Participants also self-reported the current weight of their child. This was classified by researchers as normal, underweight or overweight or obese according to standard international child growth charts.

Researchers analysed the data using standard statistical methods.

What were the basic results?

The researchers found that, overall, mothers reported that infants weaned using BLW were significantly more responsive to feelings of fullness and were less likely to be overweight compared with those weaned using a standard approach. 

They also found that infants in both groups were predominantly a normal weight, with 11.7% overweight and 3.7% underweight.

The results were independent of breastfeeding duration, timing of introduction to solid foods, and maternal control (that is, how often the mother allowed the child to eat over the course of a day).

How did the researchers interpret the results?

The researchers conclude that a baby-led weaning approach may encourage greater responsiveness to signals of fullness and healthy weight gain trajectories in infants. 

They say that mothers who used BLW had children who were perceived at follow-up as having better appetite control and lower BMI than children weaned using spoon-feeding.

Conclusion

As the authors point out, this study has several limitations that might have influenced the results:

• The sample of mothers used was self-selected, so a mother choosing to take part in such a study may not be representative of the wider population.
• The results were based on mothers self-reporting, including an estimate of the infants' weight.
• Results might have been influenced by parental attitudes, rather than the method of feeding. For example, it is possible that parents who adopted the BLW approach strongly believed in it, which may in turn have influenced the way they completed the questionnaire.
• The results may also have been influenced by infant attitudes. For example, parents of infants who were more responsive to food and less fussy to begin with may have been more inclined to follow BLW.
• Many confounders might have influenced the results, including maternal education and income and the duration of breastfeeding. However, researchers did adjust their results for some of these.
• There is no formal definition of BLW and the classification used by researchers to divide mothers between BLW and SW was odd. For example, mothers were defined as SW who may only have been spoon-feeding a minority of the time.

Many parents follow a mix of allowing infants to explore food and helping him or her along the way with some spoon-feeding. It is generally accepted that a relaxed attitude to feeding is best for the child, although this is often easier said than done.

Ultimately, it is what, rather than how, your child eats that is going to have the most significant long-term influence on their future weight. Just like adults, children benefit from a balanced low-fat diet that contains at least five portions of fruit and vegetables a day. You should also limit their consumption of sugar and salt.