Why Are People Overweight?
Today’s current obesity epidemic is increasingly a subject of social discourse accompanied by various, more or less successful health initiatives by governments, health care professionals and health practitioners. To put the rise of obesity in perspective, in 1980 just 6% of men and 8% of women were classed as obese or having a BMI of 30 or over. Today, approximately 22% and 24% of men and women are obese respectively. In the U.S., it is estimated that nearly half of all adults are overweight and a third are obese. Globally, the World Health Organisation estimates that 1.5 billion adults are overweight and 400 million are obese.
We know, of course, that being overweight can have numerous negative consequences. On a psychological level, this includes body dissatisfaction, low self-esteem, mood and depression. From a physiological perspective, being overweight is associated with increased risk of high blood pressure, poor insulin sensitivity and diabetes, chronic inflammation, metabolic disease, fertility issues, as well as increased risk of conditions such as cancer, stroke or heart disease. So, if being overweight has so many negative consequences, why is it so prevalent? The answer lies in several overlapping and complex factors.
The reason why an increasing number of people find themselves classed as obese is due to two main factors; our psychology (what goes on in our heads) and our environment (triggers and cues around us). There are three key approaches to understanding the causes of weight gain:
- Genetics,
- The environment,
- Behaviour.
Genetics
Many people claim that being overweight is part of their genetics and this may be partly true. We know, for instance, that the probability a child will be overweight is related to the parents’ weight. Having one obese parent makes you 40% more likely to be obese, which becomes 80% when both parents are obese. The probability that thin parents will produce overweight children is only around 7%.
Given these statistics, it could be argued that either our genetics or our environment are determining factors. However, studies examining identical twins raised separately have found that they are of a more similar weight than non-identical twins, who are reared together. Studies also show that the weight of people who have been adopted is more similar to their biological parents than their adoptive family. Evidence indicates that genetics play a role in body weight and body fat distribution too. It has also been suggested that a mother’s weight is a better predictor of her child’s weight than that of the father and genetics are less important as an individual becomes fatter.
However, one problem with this theory is that it doesn't account for the fact that our genetics have not fundamentally changed over the last fifty years but high-calorie, highly palatable foods have become increasingly available. For instance, studies looking at diaspora populations have found that among Nigerians living in Nigeria, 5% of the population is obese compared to 39% for those living in the U.S. For Japanese people living in Japan, the rate is 4% but this 39% for those living in Brazil. This indicates that there must be something in their environments beyond pure genetics driving obesity.
Social networking studies have shown that BMI clusters within groups. While our weight is partially determined by our parents, it is also determined by our social circle. If our friends are leaner, healthier and more active, we are more likely to be so too. However, if they also have poor eating habits and sedentary lifestyles, we are more likely to mimic this environment.
Our Environment
Given that genetics and social circumstances only account for some of the factors influencing obesity, there must be other elements at play. Today’s "obesogenic" environment, in which prevalent food advertising, cheap, processed foods and almost immediate gratification from a whole host of delicious and caloric foods, means that it is harder than ever to say no. For many, this results in decreased shopping and food preparation and more eating out and on the go. Combined with a decline in manual labour and an increase in high-stress, sedentary jobs, arrived at in cars or public transport, we have created the perfect recipe for today’s obesity crisis. Even when we try to be more active, lifts and escalators prevent us from walking and towns are designed to make walking difficult. Declining rates of sleep quality and increased stress levels play havoc with our cravings and hunger and satiety hormones. In sum, this obesogenic environment is a world in which it is easy to gain weight and it requires effort to remain thin. However, not everyone is overweight so why is it a problem for some and not others?
Why Do We Overeat?
How much we weigh nearly always comes down to energy balance. To gain weight, we must ingest more than we burn through living and activity. For those who are very overweight, they must consume equal to or more than the number of calories they need to maintain their current weight. We often think of eating as behaviour driven by the need to survive but in today’s environment, we eat for many reasons that are not hunger.
When and why we eat are mostly driven by triggers in our environment. From a young age, we begin to learn what kinds of foods we like and don’t like through our parents, friends and the media. This often takes place through a process of reward and association. For instance, you were probably told to “eat your vegetables before you can have pudding”. We are also primed to turn to food and drink as a coping mechanism when we aren’t feeling well or experiencing low mood. How often have you been encouraged to eat chocolate when you feel low or ice cream when you’re sick? Right off the bat, we begin to associate high-calorie foods as a reward that makes us feel special and better, and the “healthy” foods as boring or undesirable.
We also heavily associate food with social interaction. Food is a core element in nearly all cultures, whether that is a weekly family dinner, weddings, birthdays, religious holidays or even weekend brunch with friends. We also use food to make declarations about who we are as people; whether we are “healthy” eaters, vegetarian or “I eat anything”. Both of these factors mean that food plays a huge part in our identity and how we perceive ourselves and others.
Food also has a high association with guilt and negativity. For instance, you may try to deny yourself of a type of food you love, which only lasts so long before you break. Amid the ensuing guilt, you to overeat more than you would have otherwise done to make yourself feel better. Conversely, food also has positive and reward connotations, for instance, we often associate it with a reward or ’treat’ when we’ve been good. On a psychological level, this comes down to palatability, enticing packaging, and a strong dopamine hit to boot.
These reward cycles are all based on a concept called “future discounting”. This means that most of the time, we focus more on the immediate benefits of our actions rather than their long-term consequences. Whether it’s eating, drinking, smoking or any other pleasure-driven behaviour that has negative consequences, we perform a cost-benefit analysis in which we weigh up the pros against the cons. Most of the time, the benefits, i.e. feeling a bit better right now, win against the long-term risks of guilt, obesity, diabetes, cancer or heart disease, etc. Most of the time, what and how we eat directly correlates to what is occurring in our environment in the here and the now.
Environmental Triggers
Today’s obesogenic environment provides ever easier and cheaper access to all kinds of triggers and opportunities for mindless eating and drinking. Portion sizes have also steadily increased over the decades. Evidence shows that portion sizes for starter dishes quadrupled between 1986 and 2016 and desserts increased by 62 calories every decade. Drinks after work, lunch with friends, snacks in front of the TV, all these factors mean that consuming more and more calories now requires ever-decreasing levels of effort.
How We Eat
We are now far more likely to eat on-the-go, in restaurants or fast-food outlets, or grab something quick that requires minimal cooking when we’re at home. These types of foods tend to be highly processed and contain high levels of fat. At nine calories per gram, calories can quickly add up with even a relatively small amount of food.
Our modern highly-stressed, busy lifestyles mean we are much more likely to consume calories through snacks and drinks. If I think about many of my clients when they start with me, the average Joe works in an office and spends all day seated and stressed, working late, grabbing a ready meal on the way home and staying up watching Netflix. The creates a “hangover” effect the next day; waking up late, skipping breakfast and rushing out to work, and repeat. The ongoing cascade of stress and poor sleep ramps up cravings for high-carb, high-fat foods, often in the form of calorific coffees or snacks during the day, disrupting sleep at night and repeating the cycle. In addition, when it comes to snacking, we aren't great at remaining aware of what we are eating. When people self-report what they eat, they tend to remember their main meals but forget what they ate or drank in-between. This also means they generally don’t feel as full and are therefore more likely to overeat later.
An additional factor that strongly contributes to weight gain is our societal views of food. We see food as a mechanism to manage our emotions, show others that we care and make statements about ourselves. Managing our environment and circumstances, therefore, is key to managing what, why, when and where we eat.
Declining Activity Levels
Current government guidelines in the U.K. recommend that adults perform at least thirty minutes of exercise at least five days a week. With the advent of Uber, ever more effective public transport systems and home working, we are less active than ever before.
Despite this, it remains generally appreciated that increased activity correlates with having more energy, a lower risk of cancer, diabetes, heart attack, strokes, and much more. Many people also recognise that being active has numerous positive effects on mood, confidence and cognition. But if this is the case, why are so few of us moving as much as we should?
A big determinant of our activity levels is our social circle and its norms. For instance, we know that people are more likely to exercise if it brings social benefits, such as attending a group class or being part of a sports team. Friends and family also play an important role. Research indicates that people tend to match their body weight with those of their peers. If your friends like sitting around eating pizza and playing video games, evidently you’re more likely to be overweight than if you and your friends socialise at the gym or play a sport.
We also know that people are much more likely to become and stay active if exercise is enjoyable and easily accessible. As such, the benefits in the here and now (e.g. having fun) outweigh the costs, (i.e. feeling tired or sore). If we enjoy exercise and can incorporate into our daily lives, we are more likely to prioritise it. Once this happens, we tend to notice its positive effects on mood, which helps to reinforce it as a habit. Once someone has started the process of being more active, it is more likely to become a habit that sticks.
Major barriers to becoming more active often lie in our perceptions of our abilities and how we feel about ourselves. For instance, if we don’t know how to use a machine at the gym, we may give up for fear of looking stupid. Likewise, if we aren’t confident about how we look, the last thing we want to do is pull on tight clothing and get sweaty in public. Even the mere thought of doing this can cause severe anxiety for some.
Time and financial pressures also contribute to the picture. If you are someone who is either financially or time-poor (or both), exercise is likely to be seen as a burden. Making it easily accessible and enjoyable are therefore two main ways to bring exercise up the priority totem pole.
Most of all, our basic psychology is our biggest barrier to making healthier choices. Humans nearly always prioritise current benefits over future costs. Therefore simply telling someone that the takeaway they’re about to order could lead to heart disease likely won’t dissuade them if they’re used to using food as an emotional tool. It is only once these effects begin to impact the here and now – feeling out of breath, aches and pains, feeling depressed – that people truly start to change their behaviour. As Tony Robbins famously said, “change happens when the pain of staying the same is greater than the pain of change.”