In the ongoing effort to discover the magic pill for the obesity problem, nutrition and health researchers go about picking out individual components of diet, manipulating them in various ways, and examining the results of this manipulation. They draw a conclusion, which is usually pretty vague like “a low carb diet may play a role in controlling obesity, but more data are needed.” The lay press takes this blurry conclusion as fact, and reports to the public that scientists have found the secret to weight loss. But of course, obesity and its related health problems are not going away, despite all of the “secret cures” that have been found.
This process brings to light one of the biggest flaws with current nutrition research. When researchers study one component, food group, nutrient, or meal, they are ignoring the rest of the eating pattern. Why, when, how, with whom, and what we eat is affected by so many factors. Things to consider include education level, job schedule, cultural practices, perceived health status, taste, emotional/mental status, food access, food environment, and marketing and advertising. This isn’t even an exhaustive list. Further, a large amount of within-subject variability exists (for some people, temporary periods of depression can bring on loss of appetite, poor nutritional intake, and weight loss, despite the knowledge that a healthy diet will probably help them in the long run). When you manipulate one aspect of a person’s entire eating pattern, it may or may not affect the rest of the components of the pattern.
Nutrition researchers have the impossible job of controlling for all of these factors. Many do their best to control for some of them*, but all of these intersecting factors unfortunately cannot be sorted through. This is one reason why diet interventions often produce significant results within the context of a short-term research study, but typically aren’t as successful in the free-living public (anecdotally and observationally). And also why findings from these controlled research studies aren’t always generalizable to people living in their natural food and lifestyle environments.
A great example to shed light on the issue I’m talking about is meal skipping. In particular, breakfast. Most of us have been taught that eating breakfast is important for setting up a day of healthful food choices, improving cognition and mental focus, and maintaining a healthy weight. The argument is that eating breakfast (and consistent meals in general) increases metabolism and promotes satiety, which prevents you from overeating at later meals. For years, breakfast was the most important meal of the day, and still is according to many of us. But as is the case with much age-old nutrition advice, breakfast’s health halo has come under attack. Articles written in the lay press, as well as scientific journals1, have challenged the idea that eating breakfast helps with weight loss.**
A lot of what we know about the relationship to eating breakfast and health comes from observational data. There are so many studies that it seemed silly to pick out a few to cite here. These kinds of data show relationships and correlations but not cause and effect. Many of these studies use data collected by the National Health and Nutrition Examination Study (NHANES).*** NHANES is a government-funded ongoing study that assesses the health and nutrition status of Americans. Read all about NHANES here.
The big takeaways from these studies are that 1) habitual breakfast eaters tend to be at lower weights and have lower risks of cardiovascular disease and diabetes compared with breakfast skippers, and 2) obesity is associated with skipping breakfast.
Another source of data about food behaviors and weight is the National Weight Control Registry. It’s basically a really long observational study of over 10,000 individuals (and growing) who have lost weight (at least 30 lb from their highest body weight) and maintained that weight loss for at least 1 year. Members fill out detailed questionnaires and annual surveys to establish and track patterns that can then be associated with their successful weight loss and maintenance. According to the Registry’s website, 78% of its members eat breakfast every day7.
Randomized controlled trials looking at breakfast and weight haven’t been so conclusive2,3,4,5,6. Also, many don’t take into consideration their subjects usual eating habits.**** I believe this may have something to do with the concept that short term testing of one single component of a complex meal pattern within an individual’s complex food, socioeconomic, and cultural environment is not an adequate way to explain how that component fits into a healthy, weight-friendly eating pattern.
While perusing my Twitter feed the other night I came across a tweet sharing a recently published article about breakfast. The user posted a comment about how the study “once again” shows that breakfast has no effect on weight loss compared to skipping breakfast. I clicked on the study. It’s a randomized controlled trial comparing breakfast skipping to breakfast eating and their effects on a whole host of metabolic parameters in obese individuals2. While I understand why this person chose to highlight the weight loss findings, I think some other results are more interesting. The researchers also showed that breakfast eaters had higher physical activity levels in the morning (measured by energy expenditure) and that breakfast skippers partially compensated for the missed calories in later meals (total daily calorie intake for both groups was roughly the same, despite the breakfast skippers missing one entire meal). These two findings are actually, in my opinion, way more important than weight changes over a 6 week trial. They speak to overall lifestyle patterns and how altering a breakfast routine could affect those patterns:
- In the study, the breakfast skippers seem to have compensated for those missed morning calories by eating a little more at later meals (this was measured using food diaries, which of course have their own limitations, one being a tendency to underreport intake when someone is “watching”). One can see how over time, if this trend continued, it could potentially lead to weight gain and poor food choices.
- Breakfast eaters were more physically active in the morning, but overall total daily energy expenditure was not different between the two groups at the end of 6 weeks. In the long term, this active morning effect could lead to increased productivity at work or home, or increased planned exercise in the morning. Or perceived ability to fit in a work out during a lunch break or after work. It is possible that the simple act of eating a healthy breakfast in the morning could affect other health-related behaviors throughout the day and that over time, could result in a higher overall energy expenditure (if exercise is more feasible and enjoyable and thus engagement is maintained over a lifetime).
I do a lot of obesity and overweight counseling. I’d estimate that over half of my patients skip meals (most just skip breakfast, many skip breakfast and lunch). Based on my own anecdotal experience, I’ve seen that when a chronic breakfast skipper starts making a conscious effort to eat a balanced meal in the morning (my suggestion is usually some combination of protein and complex carbohydrate, like yogurt and fruit, or eggs and whole wheat toast), they become more mindful of their overall food choices. They become more interested and invested in healthful eating. The simple act of adding breakfast has a ripple effect on the rest of their eating pattern. And they lose weight.
Nutrition is a science in many, many important ways. But it’s also an art. Our clinical trials and data pools can only go so far when it comes to informing individual counseling. The sooner nutrition educators, dietitians, and other health practitioners realize that, the sooner we can start making a relevant impact on obesity, one patient at a time.
Fueled by whole wheat pancakes,
*But many do not, and if you’re a dietitian you know how frustrating it can be to read a study that does a poor job of this.
**These articles usually start out with a line like “For years, health experts have claimed eating breakfast was the key to weight loss, but a recent study turns that idea on its head.” 1) health experts don’t claim any one thing is the key to weight loss, and 2) one study doesn’t overturn years of previous data.
***Many (but not all) of these studies are also funded by breakfast cereal companies (Kelloggs and General Mills). This does not necessarily mean that the data aren’t reliable, especially in the case of the NHANES data. The data are already there, it’s just that cereal companies pay people to filter it and look for this particular association.
**** The exception is one recent study published in the journal Obesity6 which divided its subjects into groups based on their pre-study habits. They were either Breakfast Skippers or Breakfast Eaters. To no one’s surprise, when typical Breakfast Eaters had to skip breakfast, they reported higher levels of hunger at lunch time.