In recent years, the keto diet, originally designed for people with epilepsy, has suddenly become popular around the world, with big-name celebrities “standing up” for it and professionals questioning it, leaving frenzied dieters both excited and confused. Is the keto diet good or bad?
Two reports in the journal Cell Metabolism last year suggested that the keto diet could mimic the calorie-restricting effects of dieting and allow middle-aged and older mice to live healthier, longer lives.
Previously, JAMA published an article describing that in an 8-week clinical trial, obese seniors aged 60-75 lost 9.7% of their body weight on a keto diet, compared to only 2.1% on a low-fat diet.
Shortly after the article was published, the European Journal of Nutrition refuted the article, stating that the short-term weight loss effects of the keto diet were mixed, and that there was no evidence to support the long-term effects, safety, and health benefits of the keto diet, and that the keto diet was difficult to maintain over the long term.
Why the difference in opinion about the effectiveness of the keto diet for weight loss? Are the results of clinical trials of the keto diet for weight loss trustworthy?
Clinical Trials Did Not Consider Potential Effects of Gut Microbiome
A “keto diet” is a fat-rich diet in which fat is broken down in the liver to produce ketone bodies, including acetoacetate, hydroxybutyrate, and acetone. A starch-rich diet may be referred to as a “glucogenic” diet because starch is broken down in the digestive tract to produce glucose.
Another characteristic of a keto diet is that it is low in carbohydrates, and its hypoglycemic effect mimics starvation-promoted autophagy (waste utilization), while the lack of sugar in the brain promotes ketogenesis (lipolysis), but the high fat stimulates bile acid secretion, leading to harmful intestinal bacterial overgrowth inducing inflammation and turning nutritional obesity into inflammatory obesity.
Of course, ketone bodies can partially counteract the harmful effects of inflammation, but their effectiveness varies from person to person. Those who eat a lot of meat and have a lot of harmful gut bacteria will do more harm than good on a keto diet, and vice versa. This is why previous clinical trials of keto diets have shown mixed or no significant differences in weight loss outcomes.
Keto Diet Excludes Vegetables And Fruits
The keto diet is an artificially unbalanced diet that is high in fat and low in sugar and does not include fruits and vegetables, whereas the Mediterranean diet is a naturally balanced diet that includes oils, fish, meat, eggs, milk, grains, legumes, fruits, vegetables, and even red wine. In addition, the Atkins diet is similar to the keto diet, while the DASH diet is similar to the Mediterranean diet.
Although the dietary fiber in fruits and vegetables is not digested by the body, it can be fermented by intestinal bacteria to produce short-chain fatty acids such as acetic acid, propionic acid, and butyric acid, of which butyric acid exerts anti-inflammatory effects by activating GPR43. Keto diets, because they do not contain dietary fiber, do not have the anti-inflammatory effects conferred by short-chain fatty acids.
The body sequentially uses the ingested nutrients, first using glucose from starch hydrolysis, then glycerol and fatty acids from fat hydrolysis, and finally amino acids from protein hydrolysis.
During strenuous exercise, glycogen stored in the muscles and liver is urgently degraded to form lactic acid for energy. It is estimated that the total glycogen reserves of the body are about 500 grams, which are consumed in a single basketball game. Young people who want to lose weight take note that adequate exercise must be achieved to eliminate fat and lose weight.
The keto diet does not contain starch, and people who eat a keto diet for a long time have no stored glycogen, but the brain can only use glucose and ketone bodies, not fatty acids, so the fatty acids can only be transported to the liver to synthesize ketone bodies, which are then supplied to the brain through the bloodstream.
The high fat in the keto diet is the biggest energy provider. If the energy provided by high fat is not consumed through aerobic exercise, it will inevitably result in excess energy and therefore, the weight loss effect of the keto diet will become more and more effective.
Anti-inflammatory Diet is a Wise Choice for Weight Loss
In addition to genetic factors, the dietary causes of obesity are mainly over-eating starchy staple foods and the conversion of excess glucose into fat leading to obesity. Secondly, high fat and protein from animal sources can induce intestinal inflammation, turning nutritional obesity into inflammatory obesity and ultimately making weight loss more difficult.
The key to diet and weight loss is the control of intestinal bacteria. Without the interference of intestinal bacteria, weight loss can be effectively achieved by eating less and moving more. However, it is not yet possible to effectively control bacteria, only to try to combat inflammation.
High-fiber (plant-derived) diets have an anti-inflammatory effect on weight loss, high-fat and high-protein (animal-derived) diets have a fat-promoting effect, and keto diets have a two-way effect of promoting and opposing fat, with weight loss effects that vary from person to person and are not easily mastered by the general population. “Sacrificing” food to lose weight or “ruining” your health to satisfy your appetite is not a perfect life! The “best of both worlds” approach to weight loss is an anti-inflammatory diet that follows the “three more, three less” principle.
Eat more coarse grains, and less fine grains, and reduce the number of meals, dinner is best to eat “70% full” to avoid eating sugar in the evening to produce fat. Exercise properly after dinner to burn off excess glucose. The dietary fiber in coarse grains is fermented by intestinal bacteria to produce short-chain fatty acids, which have anti-inflammatory effects.
Eat more tofu, peanuts, and nuts, and less pork, beef, and lamb. Do not think of a high-fat, high-protein diet as a meat-rich diet; high-fat, high-protein comes from plants, not animals. Unabsorbed protein products and amino acids can also be fermented by intestinal bacteria to produce anti-inflammatory short-chain fatty acids.
Eat more sugar-free and starch-free fruits and vegetables and less sugar- and starch-containing fruits and vegetables to avoid fat production from soluble sugars and to promote dietary fiber to produce short-chain fatty acids to fight inflammation.
In conclusion, the keto diet and exercise are beneficial for weight loss in younger people, while middle-aged and older people should allow gut regulation, diet, and exercise to work together to be effective.
