Keto diet helps with weight loss but also increases cholesterol levels

The keto diet, which gets most of its calories from fat and few from carbohydrates, can certainly lead to fat loss, but it can also clog arteries and harm your gut flora.

Also known as the ketogenic diet, this diet forces your body to use a different type of fuel. Instead of relying on glucose from carbohydrates, you rely on ketones, a type of fuel your liver produces from your fat stores, which can lead to weight loss.

Previous studies have tracked the health of people who follow a ketogenic diet compared to those who don’t, suggesting that the diet has both harms and benefits.

Now, Javier Gonzalez of the University of Bath in the UK and his colleagues have conducted the first randomized controlled trial, the best known of the medical evidence. The researchers recruited 53 non-obese people with an average age of 34. They randomly assigned about a third to a ketogenic diet, in which total carbohydrates make up less than 8% of energy intake and fat makes up more than 70%.

The remaining third of participants were instructed to follow a low-carbohydrate diet, with 5 percent of their energy intake coming from ‘free’ sugars – a type of carbohydrate found in foods such as syrup, cakes and biscuits – and 45 percent and 35 percent from other carbohydrates and fat respectively.

The remaining third consumed diets with moderate amounts of free sugars, accounting for just under 20% of their energy intake, while carbohydrate and fat intakes without free sugars were around 30% and 35%, respectively. These participants acted as the control group. Protein intake was between 15-18% across all diets.

After one month, x-rays showed that participants on the ketogenic diet had lost an average of 1.6 kg of fat. The researchers verified that participants were following the diet by measuring ketone levels in their blood, urine, and breath. Food diaries also assessed adherence to the diet.

Meanwhile, those on low-carb diets lost an average of one kilogram of fat, while those on moderate diets lost nothing. By having participants intermittently wear activity monitors to estimate their energy intake, the team found that the fat loss was due to reduced calorie intake, not increased activity, something that hadn’t been known before, Gonzalez says.

But despite greater fat loss, the ketogenic diet group had 16 percent higher levels of “bad” low-density lipoprotein (LDL) cholesterol than the control group, and 26 percent higher levels of apolipoprotein B, a protein that clogs arteries and increases the risk of heart-related events. In contrast, people on the low-carb diet had 10 percent lower LDL cholesterol levels than the control group, and no change in apolipoprotein B levels.

The researchers also found that people on a ketogenic diet had lower levels of a type of gut bacteria than those on a moderately low-carb diet. BifidobacteriaIt is known that ketogenic diets help with the production of vitamin B, which is linked to a stronger immune system. The same results were not seen in people on low-carb diets. This is probably because people on ketogenic diets consume less fiber, Bifidobacteria Level, Gonzalez says.

However, it is unclear whether the ketogenic diet truly has a negative effect on the gut microbiome, because we do not fully know what the optimal diet is or what the full effects of the ketogenic diet are. Bifidobacteria Natasha Scholer of Great Ormond Street Hospital in London says:

Additionally, while elevated apolipoprotein B levels are a concern, the elevated cholesterol levels seen in the study aren’t necessarily harmful unless they reach a dangerous threshold, Scholer said.

Longer-term studies are also needed to determine whether the weight-loss benefits of ketogenic diets outweigh potential concerns about cholesterol and gut health in obese people, Scholer said.

Ultimately, the main challenge for obese or overweight people to lose weight is following a diet, says Scholer: “Whether it’s a normal carbohydrate diet, a low-calorie diet, or a calorie-for-calorie reduced-carb diet, if you stick to it, you will generally lose weight.”