Getting into and staying in shape is hard, there’s no doubt about it, but many of us often mistake difficulty for complexity. Yes, if you’re an elite level athlete or bodybuilder, elements of your diet and schedule can get complicated, but for the rest of us just working to avoid needing a new, looser pair of pants, the mechanics of fitness are simple: burn more calories than you take in, and you’ll lose weight. Lift more weight and you’ll gain strength. Do more repetitions and you’ll gain endurance.

At a glance, those statements seem like oversimplifications, but for many Americans that have spent the better part of their lives on the couch, embracing those broad stroke realities will create a noticeable difference. Then, as your familiarity and comfort with a fitness regimen grows, you can add more complex elements to suit — tracking your protein intake, experimenting with the number of sets and reps you prefer, and so forth. Of course, much of the internet is intent on convincing you that it can’t be that easy. You need to pay a trainer, buy a diet book, eat ground up herbs, subscribe to a meal service, purchase the right stretch pants and get your master’s in Kinesiology if you ever hope to lose that spare tire!

There’s a simple explanation for the folks that want you to believe those are the requirements to lead a healthy life: they make their living by selling them to you. Don’t get me wrong, there are good supplements, good books, good trainers and great stretch pants — if that’s the sort of stuff you’re into — but none of them are make or break elements of your endeavor to become fitter. The fitness industry is booming thanks to these sorts of misconceptions, and while some were indeed born out of intentional marketing gimmicks, others are based on simple misunderstandings and still more root from outdated beliefs that we’ve come to accept as fact. In previous editions of Old Man Fitness, we’ve addressed a number of these sorts of myths and misconceptions (you can find those articles here and here) and this week we’re getting right back at it — because there are no shortage of things most of us still get wrong about getting right with ourselves.

Body Mass Index (BMI) is bullshit.

If you’ve ever looked at the scale in your doctor’s office with a bit of trepidation, it’s probably because you knew he or she would about to give you a hard time about your BMI, or Body Mass Index. BMI is painfully simple to calculate because it uses only two criteria: your height and weight. The problem with assessing your overall health using only two very basic measurements is that it fails to take innumerable other variables into account that may play a direct role in your health — like bone density or muscle mass.

I’m six feet tall and weigh around 250 pounds. According to my BMI, that qualifies me as not just grossly overweight, but clinically obese.

It really should come as no surprise that your Body Mass Index is a poor measurement of one’s health, seeing as the man who developed it (who, notably was a mathematician and not a doctor) even said so. According to Lambert Adolphe Jacques Quetelet, the Belgian who conjured up the BMI index nearly two centuries ago, the BMI calculation was intended to provide broad population averages for government projects, not to assess one’s personal health.

Nowadays, we cling to the BMI index for two reasons: it’s simple, and it allows insurance companies to charge lots of people more money. For example, my life insurance premiums went up by quite a bit after they put me on a scale and ruled me “obese.”

There are several more reliable ways to measure body fat — which BMI doesn’t address at all — and even the least accurate body fat measurement methodologies are a better gauge of fitness than BMI.

It’s not your genes that are keeping you fat.

Scientifically speaking, there is little doubt that your genes play an observable role in your propensity for weight gain and even the difficulty you may experience in your weight loss endeavors, but there’s a significant difference between “playing an observable role” and actually keeping you fat. In a peer-reviewed study published the peer-reviewed medical journal The BMJ, researchers conducted a meta-analysis of 9,563 participants across 8 controlled trials. Their conclusions will be a real bummer for your coworker that keeps lamenting her “genetics” from behind a salad covered in shredded cheese and Thousand Island dressing: that the most commonly associated “fat” genes have little effect on one’s ability to lose weight.

Or, more scientifically:

These findings show that individuals carrying the minor allele respond equally well to dietary, physical activity, or drug based weight loss interventions and thus genetic predisposition to obesity associated with the FTO minor allele can be at least partly counteracted through such interventions.”

That isn’t to say that your genes have been doing you any favors, but if you think bad genetics can offset the simple math of “calories in versus calories out,” you’re mistaken. It appears (though admittedly, the scientific jury is still out) that the biggest hurdle your genes create has more to do with making you feel full. Some people are genetically predisposed to larger appetites and slower feelings of satiation, which will keep them eating more for longer and contribute to a growing waist — that means it’s still the food you’re eating that’s making you fat, not the way your body is built. While that may seem like a harsh delivery, you should consider this good news: to bastardize Shakespeare, it is not in our genes to hold our destiny, but in ourselves.

Skipping meals isn’t a long-term solution.

Read Next: Old Man Fitness: Addressing 4 of the most pervasive fitness myths

There has been a growing contingent of well-informed fitness minded people singing the praises of intermittent fasting in recent years, and although most trainers would argue that going hungry is never the solution to your fitness woes, it is true that the method can help you drop pounds. Resorting back to that same math problem (calories in minus calories out), skipping meals is one sure fire way to reduce your daily caloric input.

The thing is, intermittent fasting and meal-skipping does work to help you drop some weight in the short term, but not any more than you would drop through the traditional method of just reducing your overall caloric intake. It’s important to note as well that even intermittent fasting doesn’t mean you can overeat during the meals you don’t skip — otherwise the benefits are lost to you.

“We can say that alternate-day fasting does produce clinically significant weight loss after a year, but it’s not better than a typical calorie-restricted diet,” said researcher Krista A. Varady, an associate professor of nutrition at the University of Illinois at Chicago.

Worse, according to Varady, a higher percentage of people relapse from fasting diets than do from calorie restricted diets — that means that, although both methods can be effective, your overall chances at success are statistically lower when you choose to skip meals rather than to manage your portion sizes.

In the interest of full disclosure, it’s important that I mention that there are a number of studies that seem to indicate that there are other health benefits to intermittent fasting — but even those leaning toward fasting but remaining objective have to admit, it’s difficult to assess whether or not those benefits are the result of fasting, or simply the result of the study participants taking in fewer calories. Fasting can indeed help you to lose weight, and you can do it in a healthy way that will prevent you from going malnourished, but ultimately, most experts agree that it’s not about when you eat, or even how often — the biggest factor in your weight loss or weight gain is what you eat and how much of it.

Images courtesy of the author unless otherwise noted.