Does Keto really burn fat? Yes, but it’s complicated.
For those who don’t know or who are considering starting a ketogenic diet, a ketogenic diet is a diet with very low carbohydrates, usually less 20g/day. The diet is designed to induce oxidation of fatty acids for energy, or in other words, metabolizing dietary and body fat for energy instead of simple and complex sugars. On such a diet, individuals would increase dietary fat intake and restrict carb intake. The paleo diet is another such diet, with slightly less restrictions on carbohydrate intake. But are these diets all that they’re cracked up to be?
There have been several studies done about the perceived effectiveness of the ketogenic diet. Some who start keto do see dramatic reductions very quickly. However, in-depth metabolic studies and meta-analyses (a study of studies), has muddied this perception. In 2016, a metabolic ward study was conducted by Hall et al, which found that the initial weight loss from starting a ketogenic diet was not coming from fat, but from fluid and nitrogen losses (suggesting loss of lean body mass).
A follow-up 2021 metabolic ward study conducted by Hall found that compared to a vegetarian low-fat diet, the ketogenic diet had more weight loss 1.77 vs 1.09, however, the weight loss from the ketogenic diet came from lean body mass. In other words, they were not metabolizing fat from body stores, they were breaking down fat-free mass.
Cardiovascular effects
There are some indications that the Ketogenic diet can have negative cardiovascular effects due to increased fat consumption. A 2002 study on the Atkins diet showed elevated LDL cholesterol in those following the Atkin’s Diet. Although the ADA has relaxed on the role dietary cholesterol plays in health, this was seen as controversial and the American Heart Association still continues to restrict cholesterol. It is the oxidation of LDL cholesterol that leads to the development of plaques that lead to arterial thickness. Particle density of LDL was initially thought to play a role — larger LDL less likely to cause atherosclerosis than LDL of lower particle size. However, the Women’s Health Study found this not to be true. Although smaller LDL was more likely to cause CVD than larger LDL, both were found to be statistically significant in causing atheroslcerosis.
So with that said, does the ketogenic diet work? Sort of. You may see weight loss, however, overall health will likely be affected. In fact, within the past several weeks several news stories have broke about the ketogenic diet.