Robert Atkins’ contentious death cast doubt on his already-controversial namesake diet. But he was onto something, apparently, because aspects of his high-fat regimen live on. Ketosis, a low-carb eating plan, promises to make people really thin, really quickly. Going keto is now a fad diet of its very own — look how good LeBron James looks! — despite concerns about its safety. In the world of crash diets, instant gratification is king, and ketosis appears to deliver rapid weight loss at full speed. That is, if you’re willing to take the risks.

Phase one of the Atkins Diet had banked on ketosis, the body’s so-called “fat-burning” mode, which seemed to live up to the hype. Under normal conditions, the body fuels itself by burning up carbohydrates, fats, and protein, in that order. That’s because the simple sugars contained in pasta, rice, and sugar are easier molecules to break down. But if your body has no linguine to digest and is desperate for game fuel, it has no choice but to burn up the fat you’ve got on hand (or on love handles). And isn’t that the weight-loss dream?

But ketosis is so-named because going low-carb causes the liver to break down fats into molecules called ketones, which can also be used a fuel source. The problem is, having too many ketones floating around can be dangerous. Diabetics unable to control their insulin levels can enter a state called ketoacidosis, when the buildup of ketones causes the blood to become dangerously acidic, which in turn messes with your organs. (At this point, ketones spill over into the urine, giving it a characteristic fruity smell. The term diabetes mellitus roughly means “pissing honey.”)

Supporters of the Atkins Diet contend that the amount of ketones present in the blood during ketosis isn’t nearly high enough to be unsafe. In fact, some argued that ketosis — and by extension, some degree of starvation — was the body’s natural state. “It’s not normal to have McDonald’s and a delicatessen around every corner,” the National Institute of Health’s Dr. Richard Veech told The New York Times at the height of the Atkins craze. “It’s normal to starve.’’

It’s true that there are always some ketones floating around, regardless of diet, because certain organs — the heart and brain — use them for fuel. Normally, they’re present at a concentration of 0.6 to 1.5 millimoles per liter. Ketones only become dangerous once that number hits 3.0 — and, if your body has its insulin under control (that is, if you’re not diabetic), you’re not likely to get anywhere close to that. Still, it’s a risk only a few dedicated individuals are willing to take.

As with any diet, ketosis is all about tradeoffs. Are you going to lose weight on it? Of course you are. To go keto is to enter starvation mode. And sure, shedding 12 pounds in a couple of weeks could decrease your risk of cardiovascular disease and type 2 diabetes, but is it worth putting your body under deliberate, long-term stress? Is it worth giving up beer? For people desperate for rapid weight loss, the answer is an emphatic hell yes. What happens when you go off the keto diet is a different story altogether.

All good things, hot bodies included, take time. Does anyone really think it’s that simple?