An interview with Clare Llewellyn, PhD, and Hayley Syrad, PhD, authors of An Appetite for Life: How to Feed Your Child from the Start
ISBN: 978-1-61519-539-8 | Publication date: May 14, 2019 Price: $16.95 US | Paperback | 352 pages
Q: How did you become interested in early-life feeding and eating behavior?
Clare Llewelyn, PhD: I’ve always been interested in children’s eating behavior because I was a very fussy eater as a child—in fact, this continued into my early adulthood. It didn’t just drive my parents mad—it affected me personally, too. It’s annoying—and embarrassing—not being able to eat many of the foods that everyone else enjoys. I felt envious of friends with adventurous palates, who could try whacky new foods with no anxiety at all.
So I have always been intrigued by the fact that we all have such a different relationship with food. Why? Where does this come from? Is it our early learning experiences with food, or do we inherit these tendencies? These are the questions I have been trying to answer through my research with twin children. People’s eating behaviors continue to fascinate me.
Hayley Syrad, PhD: I have always loved research, but during my undergraduate degree I became especially interested in eating-disorder research—particularly anorexic patients, who have such strict control over their eating habits. However that would have involved a clinical doctorate, which I was not keen on undertaking, and so I started to think at the other end of the spectrum—the people who seem unable to control their eating behavior. I ended up at the Health Behaviour Research Centre with a wonderful mentor, professor Jane Wardle, and my fascination with this area of research grew and grew. She offered me a PhD, which I grabbed with both hands—and now, here I am with a published book!
Q: The Gemini twin study has been groundbreaking in terms of what we know about infant development. What are some of the most important insights it has given you, as the leading researchers in this study?
CL: Until the Gemini study began, researchers knew virtually nothing about how babies’ appetites develop, but the prevailing view was that appetite and eating habits were largely learned—in other words, it was all about how parents feed their babies. This assumption turned out to be wrong. Parents are only part of the story. In fact, genes are a really important part of the equation, too. Right from the beginning of life, genetic differences between babies help to explain why some have really hearty appetites and others are picky eaters. Parents might play some part in shaping appetite, but genetic predisposition is incredibly important. This means that parents need to tailor their feeding strategies to suit each particular child’s eating style—there is no “one size fits all” approach when it comes to the “right” feeding approach.
HS: Gemini has also shown us the importance of both genes and environment in how obesity develops, through shaping what and how children eat. Some children are born with genes that predispose them to have a heartier appetite, which subsequently influences their food intake and can increase the risk of obesity. Importantly, we also know now that parents play a large role in their child’s eating behavior, and they influence the type of appetite that their child develops. In Gemini, children with heartier appetites consumed larger portions of food and were also more likely to be overweight, demonstrating that parents need more guidance on appropriate portion sizes.
Q: How do you think the Gemini study affected your approach to writing this book?
HS: Gemini was the impetus to write this book. There has been a huge amount of media interest in our research findings, and it was clear to us that parents needed more guidance on how to help their children develop healthy eating habits. Without Gemini, there wouldn’t be a book.
CL: Gemini challenged the commonly held view that parents are entirely responsible for their babies’ eating habits—or that, as long as you feed your baby the “right way,” they’ll develop good appetite regulation and healthy eating habits. Gemini highlighted that it’s far more complicated, and it made me think: If genes are so importantly influencing appetite from the beginning of life, what room is there for parents to shape eating habits, and how do genes and environments work together? We don’t have all the answers yet, but both genes and environment are important, and this was always at the forefront of my mind when developing practical advice. I feel like parents get blamed for feeding problems (and, in fact, any problem with a baby or child) and Gemini suggests that that’s unfair. Some babies and children are really challenging to feed, and that’s just the way they are genetically—parents can only do so much. I hope this book allows parents to relax a bit and go easier on themselves.
Q: The first part of the book is focused on nutrition during pregnancy. Why are prenatal eating habits so important to a baby’s early appetite development?
CL: Existing research suggests that food preferences might start to form in pregnancy. In the third trimester, the baby has pretty well-developed taste and smell receptors, and they swallow around one liter of amniotic fluid per day. Amniotic fluid is flavored to some extent with aspects of mom’s diet—flavors such as garlic, anise, and carrot make their way in there—so the baby is “exposed” to these flavors from the earliest-possible period of life.
We also learned from a wealth of research that repeated exposure is one of the most powerful shapers of our food preferences—put simply, we like what we’re familiar with. A small amount of experimental research has shown that babies whose moms consume carrot juice during the third trimester are more accepting of carrot- flavored food later, when they are first introduced to it in infancy—suggesting that early exposure can have lasting effects. However, it’s fair to say that this is an under-researched area—most of the research into the link between a mom’s diet in pregnancy and her baby’s appetite and food preferences have been through studies of different animal species, so we can’t be totally sure how big a deal this is for humans. But one thing’s certain: good nutrition throughout pregnancy is vitally important for your baby. Pregnancy is a period of unparalleled development, and the quality of nutrition a baby receives can have lifelong effects on their health. With this in mind, it’s a good idea to pay attention to your diet during pregnancy as much as you can, to make sure you give your baby the best-possible start to life.
HS: At first, it seems difficult to believe that what a mom eats during pregnancy can shape her child’s eating preferences, but it makes sense given what we know about the effects of smoking and alcohol-consumption on a fetus. Excessive weight gain during pregnancy can cause complications for both mom and baby, so a healthy diet is key to a healthy pregnancy.
Q: Does it make a difference whether a mother chooses to breastfeed or formula-feed?
CL: The breast-versus-formula issue is a complex one. While some health benefits are associated with breastfeeding a baby—such as protection from infection during the breastfeeding period—they should not be exclusively prioritized over the physical and mental health of the parent. For mothers who cannot or struggle to breastfeed—and for grandparents or caregivers who have fostered or adopted their baby—formula offers a safe and vital source of nutrition for your baby, and caregivers should not feel guilty or ashamed about using this option.
HS: Evidence also suggests that breast milk may reduce the risk of sudden infant death syndrome. It could boost intelligence a bit, too—but the longer-term benefits are less clear. If moms are able to breastfeed, I would advise them to do so—but this is not always possible or practical, and I also feel strongly that moms should not be made to feel guilty if they do not breastfeed or they choose to stop early. A child’s physical and mental health won’t be solely determined by whether or not they are breastfed.
Q: What are some go-to foods or meals that you recommend to new parents?
HS: Without question, I recommend vegetables as a go-to food. Vegetables contain vitamins, minerals, and fiber, and have a low energy density—fewer calories per gram—because they are low in sugar and fat. There are just 23 calories in 3.5 ounces (100 g) of spinach, but milk chocolate has 535 calories per 3.5 ounces. We can eat large quantities of vegetables without consuming too many calories, and we obtain essential nutrients from them. Many parents report that their child dislikes vegetables. The key is to introduce vegetables early—offer a variety and offer repeatedly, even if the child rejects them initially. Children can learn to love foods. I would also recommend iron-rich foods like lean red meat, poultry, eggs, and dark green vegetables such as broccoli, kale, and spinach, as well as beans and fortified food like grains and breads. Iron is crucial for healthy growth and development in infancy.
Q: Is there a difference in appetites and eating habits among infants?
CL: I would add that children don’t eat anywhere near enough vegetables—so offering them regularly, as snacks and with every meal, is really important and part of helping your child to get familiar with them (which ultimately means your child will be more willing to try and then accept and like vegetables). Another thing I would emphasize to parents is that you don’t need to buy special baby-foods or make separate meals and snacks for your child. You can just give them a bit of whatever you are eating, as long as it doesn’t contain any salt or sugar.
CL: A huge difference! And this can even be seen among siblings in the same home growing up with similar foods. Differences between babies’ appetites are, to a large extent, in their genes. This doesn’t mean it’s impossible to help your baby develop good appetite regulation and healthy food preferences, but it does mean that children are different right from the start and so the best strategies for feeding your child will depend on his or her unique eating style.
HS: Some children love food and others can take it or leave it. Genes play a huge role in children’s appetites— some people are just born with more of an appetite than others. Two key appetite traits seem to be most influential. Food responsiveness is the term we use to describe how children respond to the sight or smell of food; some children are very food-responsive and can’t walk past something tasty without wanting to eat it, whereas others are far less interested. Satiety responsiveness is the term used to describe how quickly we feel full; some children feel full after just a few mouthfuls of food, whereas others can keep eating with no off-switch. There’s enormous variation in these traits.
Q: You talk about learning to read your child’s signs. What are some examples of cues that children give to show they’re full?
CL: There are early, middle, and late signs of fullness, all depending on the baby’s age. For young babies, who are still being milk-fed: early signs are slower sucking and relaxing or extending their arms, legs, and fingers; active signs are stopped sucking, release of the nipple or teat, and getting easily distracted; late signs are pushing or arching away, turning the head from the nipple or teat, sealing the lips together, or falling asleep. With older babies, the cues are very similar but usually more overt: slow or stopped eating, turning head, looking down, pulling and arching back, fussing and crying, pushing away the spoon or fork, clenching the mouth shut, becoming playful or distracted. It’s a good idea to get to know your baby’s early and active fullness cues so you can stop as soon as he or she communicates to you that they’ve had enough.
HS: Older kids can tell us when they’ve had enough, but it can be difficult to recognize these cues in young children—especially if you feel that your baby hardly drank or ate anything. But feeding according to your child’s cues will help him or her learn to eat in response to hunger—rather than in response to emotions, for example— and to stop when they are full, rather than to keep eating just because food is in front of them.
Q: Why is it so important that new parents base the nutritional decisions for their baby on scientific research instead of the latest fads?
HS: There are so many books on feeding available to parents but virtually none of these are based on science. They tend to be based on received wisdom, old wives’ tales, and individual opinion. What scientific research tells us about developing healthy eating habits is based on samples of hundreds or thousands of children (as with Gemini). This provides much stronger evidence than one author’s experience with their own child.
CL: Based on well-designed studies of thousands (or tens-of-thousands) of individual babies and children, scientific research provides a clear overview of what does and doesn’t work for most babies as well as what’s helpful or harmful. This is the foundation of what we call “evidence-based medicine.” Compared to rigorous studies of many-thousands of babies, the opinion of one or two people—based purely on their limited personal experience—is unreliable. Historically, many nutritional practices were later found to be useless or even harmful once proper scientific studies were carried out. Parents were once advised to exclude foods that commonly cause allergic reactions during the first year of life, in order to prevent allergies—but when large, well-designed studies called randomized controlled trials were conducted, scientists discovered that the best prevention for peanut allergies (for example) in high-risk babies was to introduce them to peanuts early. Other myths have also turned out to be potentially harmful—such as needing to rest and avoid physical activity during pregnancy, and the advice to “eat for two.” Our book is based on scientific consensus across the whole field of early-life nutrition, which includes vast reviews of areas that comprise hundreds of studies.
Q: What’s the best advice you can tell new parents to give their baby the right start?
CL: Trust your baby to know when he or she is hungry or full, and let them take charge of feeding. Healthy babies instinctively know when they need to eat and when they’re done—so you can leave it to your baby to decide how much they want to have and for how long. Your job is to provide nutritious food—the catchphrase we often use is “parent provide, child decide.” The other piece of advice I would give—although easier said than done—is to try not to get too stressed about feeding. It’s really common for babies and toddlers to go through a picky stage. Babies detect stress, and feeding can turn into a battle of wills if you’re too controlling over the meal. If your baby or child doesn’t want to eat something, don’t pressure or force them. There are tons of stress-free strategies to use instead, and we give you lots of ideas in the book.
HS: I always recommend using vegetables to introduce food to babies for the first time. Since they have only had breast milk or formula, which would taste extremely bitter to us, it’s beneficial to start babies on bitter vegetables such as broccoli rather than sweeter tasting vegetables like carrot or sweet potato. Offering fruit as a first food is a wasted opportunity—we’re all born with a preference for sweetness. Most babies will eat mashed banana—but then if you offer them broccoli, it’s likely to be rejected. Offering a variety of vegetables will help babies to learn the taste of each food, and repeated offerings will help them learn to like it.
Q: What changes do you see for the future in the field of early-life feeding and appetite development? What are you researching now?
CL: So far, most of the research in this area has been observational—it simply looks at how babies are fed to determine whether or not that’s linked with their appetite and eating habits later on. But this type of research can’t tell us if the way babies are fed really causes the characteristics of their appetite and eating behavior, or if parents feed their babies in a certain way because of their eating style (in other words, whether parental feeding styles are a response to—rather than a cause of—child appetite). This is the proverbial “chicken or egg” question—we don’t really know what’s causing what. Nor do we know if it’s possible to change a baby’s developing appetite and eating behavior, given such a strong genetic basis. The only type of research that can tell us whether or not early feeding shapes a child’s appetite and eating habits is called a randomized controlled trial. This is when a large number of parents are randomly assigned to either feed their babies in a certain way or carry on as they wish, and then the appetites and eating behaviors of their babies are studied over several years. Very few of these studies of have been conducted (they are all covered in detail in the book), and these are what we need going forward. We’ve just secured some funding to develop a new trial in the UK that will do exactly this.
Another area that needs far more research is the link between early childhood eating behavior and the development of either healthy eating patterns or eating disorders in adolescence and adulthood. We have additional funding—to study infant and childhood appetite and eating behavior alongside eating patterns later in adolescence—for Gemini as well as three other large studies; combining nearly 20,000 children in the UK, the Netherlands, and Norway. This will allow us to identify early eating behaviors that become problematic later— opening up the possibility of very early interventions to prevent an eating disorder from developing.
Lastly, we need far more studies on the role of dads! There is virtually no research here, and yet dads play an important role in their children’s care.
HS: Gemini has shown us key factors that shape children’s eating habits but there is still so much we don’t know. I would love to see another Gemini study conducted with much larger samples of children in a larger number of countries, to really get to the bottom of the importance of early-life nutrition. There were various factors that Gemini did not look at—such as energy expenditure, which is an important part of the equation when it comes to obesity. In Gemini, we collected extensive dietary data when the children were about twenty- one months old; but to aid our understanding of the role of breast milk versus formula in children’s health, I would like to see data collected much earlier in life.
This interview can be reprinted in part or in its entirety with the following credit line:
Interview with Clare Llewellyn, PhD, and Hayley Syrad, PhD, authors of An Appetite for Life: How to Feed Your Child from the Start (The Experiment, May 2019); theexperimentpublishing.com.