Scientific evaluation of weight loss aids: the capsaicin effect and the long-term risks of low-carb diets.

The Chili Pepper Diet: I. Does Chili Pepper Really Help You Lose Weight? The chili pepper diet, as the name suggests, aims to achieve weight loss by eating chili peppers. This method originated in Japan. The core of the chili pepper diet lies in capsaicin, a chemical substance abundant in chili peppers. Scientific research has found that this substance can produce certain weight-loss effects through multiple mechanisms. Capsaicin can activate the TRPV1-related signaling pathway, inhibit fatty acid synthesis, promote energy consumption, and reduce lipid accumulation, significantly reducing the weight of diet-induced obese mice. Capsaicin can also enhance sympathetic nerve activity, thereby suppressing appetite and increasing energy metabolism. Japanese researchers have verified in human trials the inhibitory effect of eating chili peppers for breakfast on the intake of carbohydrates, fats, and proteins. Furthermore, human trials have also confirmed that capsaicin can significantly reduce postprandial blood glucose, insulin, and C-peptide levels, and improve insulin resistance, which may also play a role in controlling obesity. Although basic research suggests potential weight-loss benefits of capsaicin, its effects in high-quality population studies have been less than ideal. In a rigorously designed randomized controlled trial, the experimental group took 6 mg of capsaicin daily for 12 weeks. Compared to the placebo group, both groups experienced average weight loss, but the difference in weight loss between the two groups was not statistically significant. However, in domestic controlled trials, after 4 weeks of oral capsaicin intervention in 10 overweight volunteers, their BMI, degree of obesity, visceral fat area, body fat percentage, and hip circumference significantly decreased compared to before the intervention. A meta-analysis including 9 original studies showed that taking chili peppers/capsaicin could increase the average daily energy expenditure of overweight and obese individuals by 58 kcal, which is only about 1/30th of the total daily energy intake of an average person, indicating that relying solely on chili peppers for weight loss is far from sufficient. In conclusion, while the weight-loss effects of chili peppers have yielded relatively positive results in animal models, their effectiveness in human populations is not significant. In other words, chili peppers can only be used as a supplementary food in the weight-loss process; relying entirely on chili peppers for weight loss is unrealistic. Currently, there is a lack of research on the long-term effects of consuming chili peppers for weight loss. Whether the body will develop tolerance after long-term consumption of chili peppers, leading to a decrease in weight loss effectiveness, is also unknown. Secondly, while chili peppers are a good food, excessive consumption is not beneficial. Chili peppers are a food with a long history, exceptionally rich in Vitamin C and possessing rich nutritional value. Although consuming small amounts of chili peppers (low doses of capsaicin) may have a certain weight loss effect through mechanisms such as increased energy expenditure, excessive consumption and increased capsaicin intake can cause various harms to the body. In animal experiments, large doses of capsaicin can cause the death of some neurons in experimental rats, resulting in permanent loss of pain sensation. Large amounts of capsaicin can also cause symptoms such as congestion, edema, and spasms in the gastrointestinal mucosa of experimental animals. Due to the current popularity of the "no spice, no life" food culture in my country, hot pot and other dishes often contain large amounts of chili peppers to stimulate appetite, and discomfort symptoms after consuming hot pot and other foods high in chili peppers are common. A survey in Chengdu revealed that 84.7% of people experienced discomfort after eating hot pot. The main symptoms included dry mouth, oral ulcers, sore throat, diarrhea, abdominal pain, burning sensation in the anus, frequent bowel movements, and constipation. The amount of hot pot consumed, the frequency of consumption, and the spiciness level were the most significant factors influencing the severity of these symptoms. A study in Mexico found that people who ate chili peppers were many times more likely to develop gastrointestinal cancer than those who didn't. Whether it's hot pot or other forms of chili seasoning, a large amount of oil is usually added during processing. For those trying to lose weight, consuming processed chili peppers also increases oil intake, which is very detrimental to weight loss. Therefore, even when using chili peppers as an aid in weight loss, attention should be paid to the processing methods to avoid greasiness and excessive consumption that could lead to discomfort. The "eat more fat, eat more meat, eat less grain" diet is a weight loss method where "controlling your diet and exercising" is key. However, for food lovers, "controlling your diet" is undoubtedly an extremely painful task. In recent years, the claim that "eating more fat and meat and no grains can easily achieve a perfect figure" has quickly become popular online, gaining support from many people trying to lose weight, especially meat-eaters. However, is dieting without grains really effective? Will it have any impact on our health? This dietary model was actually proposed as early as the 1950s and 60s; its essence is a typical low-carbohydrate diet for weight loss. I. The Currently Popular Low-Carbohydrate Diet A low-carbohydrate diet (LCD) restricts carbohydrate intake and replaces it with foods rich in protein and/or fat, as well as other low-carbohydrate foods, thereby limiting energy intake and increasing protein and fat consumption. Currently, there is no unified quantitative definition of a low-carbohydrate diet domestically and internationally. According to most clinical studies, a daily carbohydrate intake of less than 150g, or a carbohydrate-provided energy ratio of less than 40%, can be considered a low-carbohydrate diet. Based on intake, a broad definition of a low-carbohydrate diet can be divided into low-carbohydrate diets (20%~40%), carbohydrate-restricted diets (10%~20%), and very low-carbohydrate diets (5%~10%). Currently popular low-carbohydrate diets include: the Paleo diet, the Atkins diet, the ketogenic diet, the low-carbohydrate Mediterranean diet, the low-carbohydrate high-protein diet, and the zero-carbohydrate diet. In all of these low-carbohydrate diets, the energy ratio from carbohydrates is far lower than the recommended 50% carbohydrate energy ratio plus 4g water in dietary guidelines. Obese individuals can store up to 350-500g of muscle glycogen and 100g of liver glycogen. Small-sample studies suggest that long-term low-carbohydrate diets can reduce weight by mobilizing fat for energy; reducing insulin secretion and inhibiting body fat synthesis; or by regulating different hunger-related hormones to suppress appetite and reduce intake. However, in reality, the weight loss effect of low-carbohydrate diets is not better than that of restricting energy and fat, and it does not have a scientific advantage in terms of health effects. Moreover, long-term replacement of carbohydrates with high-protein, high-fat diets has significant health risks. Prolonged consumption of fat for energy can lead to ketosis or ketonuria, causing ketoacidosis. Mild cases may present with nausea and vomiting, while severe cases can result in dehydration, shock, and even death. Long-term high protein intake also increases calcium loss, purine intake, and the burden on the liver and kidneys, increasing the risk of gout, osteoporosis, non-alcoholic fatty liver disease, kidney stones, and renal dysfunction. From a carbohydrate perspective, carbohydrates are an important component of human tissues, participating in cell composition and various functional activities, and are the main source of blood glucose. A long-term lack of carbohydrates in the body leads to a drop in blood glucose levels, easily causing hypoglycemia and hypotension, such as dizziness, blurred vision, cold sweats, and weakness. Glucose is the only energy source the brain can utilize; a long-term lack of glucose can also damage the brain, causing symptoms such as memory loss. Severe hypoglycemia can even damage brain cells, causing irreversible brain damage. Meanwhile, due to a limited variety of foods, the intake of nutrients other than fat and protein, such as certain vitamins, dietary fiber, and trace elements, will be significantly reduced, easily leading to problems such as constipation, gut microbiota imbalance, and malnutrition. IV. Choosing a Scientific and Reasonable Dietary Pattern. Scientific dietary management is crucial for healthy weight loss. Choosing appropriate staple foods not only increases satiety and reduces food intake, but also activates key enzymes in the body's anabolic metabolism, increases dietary fiber, provides various minerals and vitamins, and maintains the body's nutritional balance. Recommendation:

Limit total energy intake and increase physical activity;

A diverse diet with a focus on beans and whole grains, and moderate intake of tubers;

Avoid refined pastries, breads, fried foods, and other foods that are high in oil, sugar, and energy density;

Eat a light diet, low in salt and oil, and choose appropriate cooking methods;

Eat more vegetables and a moderate amount of fruit;

Changing the order of meals, to soup, vegetables, meat, and staple food in that order, can help reduce food intake.

Eat slowly and mindfully.