We’ve shared over several posts the health risks that may result from obesity. Carrying extra weight can increase the risk of many complications related to your heart, vascular system, higher risk of diabetes, increased pain levels, and more. Medical providers often urge those with a higher BMI to lose weight to reduce potential health issues. Here enters the long-standing debate of the benefits of “fit but fat”, where increased levels of physical activity are encouraged to increase cardiovascular fitness in an effort to lessen the risk of a variety of issues, but the focus isn’t primarily on weigh loss.
What is “fit but fat”?
This isn’t a new topic, with early studies going back as far as 1999, when two large scale studies suggested that people that were obese could still be fit in the cardiovascular sense. One of the studies showed that obese men could reduce their risk of heart disease significantly through exercise, even when they didn’t lose any weight.
Since then, additional research has backed up those findings with many also supporting the benefits of shifting the focus from weight loss alone, to overall fitness and increased physical activity. Dr. Glenn Gaesser, a professor at Arizona State University and co-author of a new review, shares “Current obesity treatment guidelines do not even mention ‘fitness’ and only encourage physical activity as a means to facilitate weight loss. This approach ignores the major improvements in mortality and disease risk associated with increased physical activity and improved fitness in the absence of weight loss. [Evidence shows], improving fitness by increasing physical activity is associated with greater reductions in mortality risk compared to weight loss.“
“Fit but fat” vs. calorie restriction
Many studies show that severe calorie restriction is more effective than exercise training in reducing fat stores, but calorie restriction over long periods is most often not sustainable. The focus on treating obesity with a singular focus on weight loss is often futile due to the inability to maintain the weight loss, in addition to many people being unable to reach their weight loss goals at all. Both situations can lead to people gaining back any weight they’d lost and potentially then returning to their previous lifestyle and diet habits. At times, people will make additional efforts to lose weight but often find their experience is repeatedly that of losing weight then gaining it back- often referred to as “weight cycling”, which has been found to be associated with negative health outcomes.
Dr. Gaesser addressed whether unhealthy practices such as extreme calorie restriction could explain the limited benefits of weight loss in individuals with obesity.
“Unhealthy weight loss practices are much more common among persons with a high BMI who also attempt weight loss more frequently. We contend that it is entirely plausible that [many] of the health risks associated with obesity are due to the adverse effects of weight cycling. Weight cycling is associated with increased mortality risk, and weight cycling is more prevalent among persons with obesity.”
Three recent meta-analyses support that weight cycling is associated with increased risk of cardiovascular disease-related mortality, as well as higher risk of all-cause mortality. This suggests that traditional methods of pursuing weight loss as the primary way to reduce mortality risk (along with other obesity related health issues), when resulting in weight cycling, may inadvertently be working against the intended benefits of weight loss.
Proponents of the “fit but fat” approach, which encourages increased physical activity to improve cardiovascular fitness also point out that studies that focus on weight and BMI don’t acknowledge the limitations of those two metrics in explaining an individual’s health. BMI, for example, doesn’t consider gender, fat mass vs. lean muscle mass, and body fat distribution. One source shares that in most cases, studies on BMI and chronic disease risk are observational, meaning they examine a snapshot in time and don’t involve an intervention (e.g., dietary changes or physical activity programs), and so they can’t prove cause-and-effect relationships.
Furthermore, studies do not consistently show an association between weight loss from calorie restriction and exercise and a decrease in mortality risk. On the other hand, there is more consistent evidence supporting that cardio-respiratory fitness can significantly reduce and potentially eliminate the mortality risks associated with high BMI. The most recent review found that cardiovascular fitness (measured by the ability of the cardiovascular and respiratory system to sustain physical activity over time), was at least as effective as weight loss in decreasing mortality risk while also avoiding the “weight cycle” that may completely deter people from addressing obesity.
Cardiovascular exercise is also an effective way to reduce two types of fat- visceral adipose tissue, which is around the internal organs in the abdomen, as well as fat that is in the liver. Reducing these two types of fat decreases the risk of cardiovascular disease and type 2 diabetes. Sources share that even when weight loss is not achieved, a clinically relevant reduction in the fat stores in the liver and visceral adipose tissue can occur with exercise training, further supporting that “fit but fat” can reduce the risk of significant health risks, despite not necessarily resulting in immediate weight loss results.
What does this all mean?
Before we continue- one thing should be made clear. The reviews and studies that support focusing on cardiovascular fitness rather than calorie restriction as a weight loss method aren’t saying that obesity and carrying extra weight do not harm your health. Or even that weight shouldn’t be considered when addressing overall health. An abundance of evidence shows that obese and overweight people have higher risk of diabetes, high blood pressure, and high cholesterol- all of which can cause severe health issues like a stroke or heart attack, along with increased levels of pain and even higher rates of depression.
Proponents of the “fit but fat” approach emphasize that weight loss, when pursued using tactics that become unsustainable, can actually cause more harm. Research shows that for any person, regardless of weight, an increase in physical activity will provide a variety of benefits, from increased cardiovascular fitness, to improved mental state, better sleep, increased confidence, more opportunity to build a supportive network, and more. That weight loss is likely to result from increased physical activity is an additional benefit that only further supports overall wellness. The conversation of “fit but fat” should be looked at as more of a re-framing of the traditional approach of weight loss as the primary avenue to achieve an improved physical state.