Does thinking that you are fat make you fat?

What we have suspected for some time – that constantly being bombarded with pictures of skinny people – may have a negative impact on our own thoughts, feelings and behaviour after all. Indeed, despite the images of super-thin bodies become omnipresent and infecting more and more of our waking moments, at a population level we are becoming more overweight and obese.

It looks like the kind of comparison that this ubiquitous imagery could encourage has a significant impact. Researchers at the Norwegian University of Science and Technology have found that normal weight teenagers who perceive themselves as fat are more likely to grow up to be fat. This is the first study to look at the relationship between perceived weight and actual weight in a longitudinal study of teenagers and young adults. 1196 normal range weight adolescents were followed up as young adults 11 years later. After controlling for covariates such as age, sex etc, adolescents who perceived themselves as overweight had a significantly larger weight gain into young adulthood that adolescents who perceived themselves as having a normal weight (0.66 BMI units; 3.46cm waist circumference). This was unrelated to levels of physical activity.

Thinking that you are fat as an adolescent – even when you are not – can lead to become significant fatter as an adult. 22% of girls rated themselves as overweight as teens, compared to 9% of boys – this might be due to media focus on body image focusing on girls – especially at the time that these young adults were teens. Worryingly, 59% of girls who felt fat as teens became overweight as adults. If we consider waist circumference, 78% of teens who initially perceived themselves as fat later became overweight as adults.

It’s difficult to know what causes the increase in weight, and it is likely to be complex. We know that stress can cause an increase in weight – the authors suggest that the psychosocial stress of not being your ideal body type (wherever that idea may come from), as well as thinking of yourself as overweight can lead to weight gain. Perhaps another explanation is that seeing yourself as fat can lead to skipping of meals – and we know that dropping breakfast has been linked to obesity through various mechanisms.

The lesson I take away from this is the importance of anchoring our self-perceptions of weight in fact, rather than glossy imagery that we come across every day. This is even more important in the crucial developmental years of adolescence, where we try to understand and balance the plethora of information telling us how we should be adults and how to be acceptable to ourselves and others. Challenging this information, and developing alternate pathways through healthy diet, exercise and mental wellbeing is so important, and is a set of skills that needs to be taught.

Does running mess with your guts?

A tricky and somewhat delicate topic to tackle, but a real problem for some.

Exercise does provide immediate benefits for your gastrointestinal system. There appears to be a dose-response relationship between exercise intensity and health. Mild to moderate levels of exercise can help to protect against colon cancer and constipation, as well as other conditions. It can improve digestion and elimination through strengthening muscles of the abdomen and stimulating intestinal muscles to help move things along more quickly. However, intense exercise has been associated with heartburn, gastric reflux, nausea, vomiting, abdominal pain, diarrhea and even gastrointestinal bleeding. Exercise sometimes slows down digestion as energy is conserved for exercise activity. Gut ischemia, or a lack of blood supply through various causes, is thought to be at the heart of some of the gastrointestinal problems that people experience when exercising.

Research reported in this paper seems to find that those that exercise the most intense – elite athletes – are hit particularly hard by these problems. About 25 to 50% of these athletes are affected so badly by symptoms of gastrointestinal distress that it can put them off training or competing. A dehydrated state can also make these symptoms worse.

Interestingly, the frequency of these symptoms seems to be twice as high for endurance runners than those participating in other endurance sports such as swimming or cycling, and one to three times more frequent in elite athletes compared to those participating in more recreational exercise..

Here’s what you can do to avoid negative side effects of exercise if these are a problem for you:

• To be ultra-safe, allow two hours after a meal before you exercise and do not exercise on a full stomach. I always leave an hour at least, but if you continue to have problems, try longer
• Practice light exercise to improve the efficiency of the digestive system
• Check your meal composition, water intake, and medications – if these aren’t right, it can make the problem worse
• Avoid caffeine before exercise. It can sharpen you up, but loosen you up too – it irritates the bowel
• Light exercise such as yoga and pilates can also improve digestive system functions by reducing stress and anxiety levels, which can cause digestive disorders, too.

Good luck!