Yesterday, I wrote about new research showing that you can reverse Type 2 diabetes. All you have to do is lose weight, and keep it off.

But, as any yo-yo dieter knows, that’s easier said than done. The vast majority of people who lose weight regain what they lost (and often more) within twelve months.

Inevitably, that’s because people (especially we impatient folks here in the US) tend to lose weight through inherently unsustainable approaches. Sure, you can eat cabbage soup for a few weeks, and drop ten pounds. But unless you’re planning to eat just cabbage soup for the rest of your life (and for a slew of reasons, from malnutrition to culinary misery, I wouldn’t recommend it), you’re going to return to your normal eating patterns eventually. And the scale will swing back up once you do.

The solution, then, is what I think of as the ‘toothbrush rule’.

Most of us are well aware that toothbrushing isn’t a short-term intervention. Instead, we’ve accepted the idea that we need to keep brushing our teeth as long as we’d like to still have teeth.

Nutrition (and health in general) works the same way. The only things that are successful in the long-haul are things we’re able to keep doing over that long-haul.

That means, first, that if you can’t imagine doing something for the next ten years, it’s a waste of your time and energy to try it for the next ten days.

And second, it means that when you’re thinking about improving your nutrition, exercise and lifestyle, you should be thinking in terms of habits, about small relatively painless things you can do daily until they become second nature.

Only when you turn health into habit can you keep it going indefinitely. That’s why research has shown the single best predictor of continuing to maintain weight loss is how long you’ve already maintained that weight loss.

And it’s not just your brain that adapts to those kinds of long-term habits; the rest of your body is a highly adaptable system, and eventually it will swing around to back you up, too. For example, right after you lose weight, your pancreas secretes large amounts of ghrelin, a hormone that drives the feeling of hunger. But research has shown that if you maintain the weight loss, ghrelin levels (and therefore your sense of hunger) slowly drop back to where they were before you lost weight. In other words, keeping off the weight gets easier the longer you keep it off.

So, if you want to get healthy, and to stay healthy, think about the toothbrush rule. Build your approach based on sustainable habits, and only take on things that you’re willing to keep doing as long as you’d like to keep your health.

In a healthy body, your pancreas secretes insulin, to manage the level of glucose in your bloodstream.

As you gain weight, eat poorly, and remain inactive, the amount of glucose circulating in your body increases. So your pancreas has to work overtime, secreting more and more insulin to try and keep up.

After a while, however, your pancreas basically just burns out. It stops secreting insulin altogether, leaving toxic levels of glucose circulating. That’s called type 2 (or adult onset) diabetes.

Type 2 diabetes is bad news. It increases your odds of death in a given year by 2.5x, and it leaves you vulnerable to all kinds of non-lethal but still crappy complications, like going blind and having your toes and fingers amputated.

By now, about 10% of the US has type 2 diabetes, and another 30% have blown out their pancreases sufficiently to be classified as ‘pre-diabetic’.

According to new research, however, those people aren’t permanently screwed.

In a group of patients who lost weight through six weeks on a very low calorie diet, and who then maintained that weight loss for six months, nearly 50% reversed their diabetes entirely. Their pancreases ‘woke back up’, and started secreting insulin again.

This extends research by the NIH on pre-diabetics, who similarly reversed the disease by losing weight and getting active.

In other words, if you’re pre-diabetic or even have full-blown type 2 diabetes, it’s not too late. You can take matters into your own hands, get in shape, and cure yourself.

Sure, that takes hard work. But let’s be brutally honest: it’s still much better than being blind, toeless and dead.

One of Composite’s core principles is that ‘science has the right answer.’ In everything we do, we’re guided by current research, and committed to empirical testing.

So some clients are surprised to find that our recommendations occasionally conflict with what their physicians tell them, or run against the current apparent consensus in the world of public health.

As I first dove deep into the science of nutrition, exercise, and health, I, too, was surprised by that same disjoint.

By now, however, I think both conflicts are structural inevitabilities.

In the case of public health, the creation of policy is (not surprisingly) inherently political. And once policy is implemented broadly, change comes around very slowly, like turning a battleship.

Of course, most of us already know that science alone doesn’t rule the policy day. Consider the ‘debate’ over climate science, which has raged for decades despite a lack of any underlying debate in the research itself.

As Otto von Bismarck once quipped, “laws are like sausages, it is better not to see them being made.” Nonetheless, to understand the difficulties in health policy, it’s hugely instructive to follow at least one piece of legal sausage being ground out. To that end, I highly recommend Gary Taubes’ great decade-old piece from Science, “the (Political) Science of Salt.”

In it, Taubes tracks the birth of the FDA’s official recommendation to reduce sodium intake, despite very little (and often conflicting) research supporting the idea at the time. Mainly, the recommendation sprang from the efforts of a few particularly vocal and politically savvy proponents.

And Taubes explores why the recommendation has continued for decades, even after more recent large meta-studies have demonstrated that clinical trials just don’t support a general recommendation to reduce salt intake. In short, even in the face of increasingly overwhelming amounts of new research, many scientists simply have trouble changing tack mid-career where it disagrees with their own early-career findings.

As physicist Max Planck once put it, “a scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die.”

(Sadly, that actually seems to be the case. A great study from the National Bureau of Economic Research tracked more than 12,000 elite scientists across a slew of different fields, and discovered that substantive and influential new research was most likely in a given field only once one of its current giants retired or passed away.)

In other words, public policy isn’t always the best source of health answers, especially if you’re looking for the most up-to-date ideas.

As for physicians, the difficulty is simpler, and less sinister: there’s just too much new stuff to know to expect any single person to keep up with all of it. Indeed, in any single specialty, following all the journal research is a full-time proposition. Expecting physicians to follow, equally closely, research in peripheral fields – like nutrition or exercise science – is nearly an impossibility.

As a result, most physicians know their own fields inside and out, but are often slightly further behind as they push further away from that core.

For example, for decades, medical education and public health policy agreed that reducing dietary cholesterol was a smart approach to lowering blood cholesterol.

Over time, however, repeated attempts to prove that idea failed. So the public health policy world quietly backed away from it. Last year, the FDA’s annual food guidelines no longer put a daily cap on cholesterol intake, explaining that cholesterol was no longer “a nutrient of concern.”

Yet at the same time, a national survey of physicians found that more than 70% of general practitioners still erroneously believed that “eating cholesterol-rich foods has damaging cardiovascular effects.”

(More dismayingly, 40% of nutritionists also still held that incorrect belief, though I’ll put that aside for another time.)

Even in an area where enough decades of research had accumulated to allow the slow wheels of public policy to come around, the vast majority of practicing physicians still hadn’t quite caught up.

Again, I don’t fault physicians for this. They’re busy keeping current on oncology or pulmonology or nephrology, which is precisely what they should be doing. But we also shouldn’t be surprised that, outside of their deep areas of expertise, they’re not always the single best source for what’s right.

All of which is to say: when it comes to nutrition and exercise, while health policy and physicians are hugely important, our first line of national defense, it also doesn’t hurt to look for a second opinion. Especially if that second opinion is one backed up by piles of current, peer-reviewed research. Usually, it’s not that policy and physicians are wrong, they’re just a bit out of date.