9 popular weight loss diets under the microscope (intermittent fasting)
After looking at the Paleo diet, the vegan diet, low-carb diets, the Dukan diet and extremely low-fat diets in the first part of this article, we will take a closer look at the Atkins diet, the HCG diet, the Zone diet and intermittent fasting in this second part of this article.
6 The Atkins diet
The Atkins diet is the best-known low-carb weight loss diet. Its advocates insist that you can lose weight by eating as much protein and fat as you want, as long as you avoid carbohydrates.
The main reason that low-carb diets are so effective for fat loss is that they reduce appetite. As a result, you eat fewer calories without having to think about it (32, 40).
How this diet works: The Atkins diet is divided into four phases. It starts with an introductory phase, during which you eat less than 20 grams of carbohydrates per day for two weeks. During the other phases, carbohydrates are slowly added back to the diet as you approach your weight goal.
Weight loss: The Atkins diet has been studied extensively and these studies conclude that it leads to weight loss faster than other low-fat diets (52, 81).
Other studies note that low-carbohydrate diets are very helpful for weight loss. These are particularly successful when it comes to reducing abdominal fat - the most dangerous type of body fat located in the abdomen. (30, 31, 32, 33, 34, 35, 36)
Other benefits: Numerous studies show that low-carb diets like the Atkins diet can reduce risk factors for disease including elevated blood triglyceride levels, high cholesterol levels, high blood sugar levels, high insulin levels and high blood pressure (34, 42, 43, 44, 45).
Compared to other weight loss diets, low-carb diets are also better at improving levels of good HDL cholesterol, triglyceride levels and other health markers (52, 81).
The cons: Like other low-carb diets, the Atkins diet is safe and healthy for most people, but can cause problems in rare cases.
Summary: The Atkins diet is a low-carbohydrate weight loss diet. It is effective for weight loss, but also has many other health benefits.
7 The HCG diet
The HCG diet is an extreme diet that can result in very rapid weight loss of up to 0.5 - 1 kilogram per day. Its advocates claim that it increases the metabolic rate and fat loss without causing hunger (82, 83).
HCG (Human Chorionic Gonadotropin) is a hormone that is present in high levels in the body during pregnancy. It signals to the woman's body that she is pregnant and maintains the production of hormones that are important for the development of the fetus. HCG is also used to treat fertility problems (84).
How this diet works: The diet is divided into three phases. During the first phase, you start by taking HCG supplements.
During the second phase, you follow an ultra-low calorie diet with only 500 kcal per day in combination with HCG drops, pellets, injections or sprays. This weight loss phase lasts 3 to 6 consecutive weeks.
During the third phase, the HCG intake is stopped and you slowly start to increase your food intake.
Weight loss: The HCG diet causes weight loss, but several studies conclude that the weight loss is based solely on the ultra-low calorie intake and has nothing to do with the HCG hormone (82, 85, 86, 87). Furthermore, it has not been observed that HCG reduces hunger.
Furthermore, HCG cannot have any effect, at least when taken orally, which for legal reasons is often in homeopathic form, purely from a biological point of view. HCG is a peptide hormone that consists of almost 200 amino acids. This hormone is destroyed in the digestive tract and broken down into its amino acids.
And even if traces of HCG reach the intestine, where nutrients are absorbed into the bloodstream, they cannot pass through the intestinal wall as it is only permeable to free amino acids or peptides consisting of a maximum of 2 to 3 amino acids. Other benefits: Aside from weight loss, there are no documented benefits of the HCG diet.
Cons: Like most ultra-low calorie diets, the HCG diet can result in muscle loss, which in turn results in a reduced ability to burn calories (61).
Such severe calorie restriction reduces the amount of calories your body burns. This is because the body feels like it is starving and therefore tries to conserve energy (63).
In addition to this, most alleged HCG products on the market do not contain any HCG, which is also related to the fact that HCG is only available on prescription except in homeopathic doses and real HCG supplements would therefore be illegal. Ultimately, only HCG injections are able to increase the blood levels of this hormone.
In addition, this diet has many side effects including headaches, fatigue and depression. There is also a case report of a woman who developed blood clots that were most likely caused by this diet (83).
In the USA and many other countries, the HCG diet is not approved even under medical supervision (88).
Summary: The HCG diet is a diet for rapid weight loss. It is not based on science and can cause muscle loss, headaches, fatigue and depression.
8 The Zone Diet
The Zone Diet is a low glycemic load diet that limits carbohydrate intake to 35-45% of daily calorie intake and sets protein and fat intake at 30% of total calories each (89).
This diet only recommends the consumption of carbohydrates with a low glycemic index (GI). The GI of a food is an estimate of how much that food will raise blood glucose levels after consumption.
The Zone Diet was originally developed to reduce diet-induced inflammation, induce weight loss and lower the risk of chronic disease (89).
How this diet works: The Zone Diet recommends that each meal consist of 1/3 protein, 2/3 colorful fruits and vegetables, and a dash of fat, by which is meant monounsaturated fat such as olive oil, avocados, or almonds. This diet also limits the consumption of high-glycemic carbohydrates such as bananas, rice and potatoes.
Weight loss: Studies with low-glycemic diets are quite inconsistent. While some conclude that these diets promote weight loss and reduce appetite, other studies show very little weight loss compared to other diets (90, 91, 92, 93).
Other benefits: The greatest benefit of this diet is a reduction in risk factors for heart disease, such as a reduction in cholesterol and triglyceride levels (92, 94, 95, 96, 97).
One study suggests that the Zone diet can improve blood sugar control, reduce waist circumference and reduce chronic inflammation in overweight or obese people with type 2 diabetes (98).
The cons: One of the few disadvantages of this diet is that it reduces the consumption of some healthy carbohydrate sources such as bananas and potatoes.
Summary: The Zone diet is a low-glycemic diet. Some studies on weight loss are inconsistent, but this diet improves important health markers and reduces the risk of heart disease.
9. intermittent fasting
Intermittent fasting alternates cyclically between periods of fasting and eating. Instead of restricting the foods you can eat, this diet controls when you eat these foods. As such, intermittent fasting can be considered more of a dietary regimen than a diet.
The most popular variations of intermittent fasting include:
- The 16/8 method: this method involves skipping breakfast and limiting the daily eating period to eight hours, which means fasting for the remaining 16 hours.
- The eat-stop-eat method: This method involves 24 hours of fasting once or twice a week on two non-consecutive days.
- The 5:2 diet: In this method, you limit your calorie intake to 500 to 600 kcal on two non-consecutive days. On the five remaining days, the calorie intake is not restricted.
- The Warrior Diet: In this method, you only eat small amounts of raw fruit and vegetables during the day and a large meal in the evening.
How this diet works: Intermittent fasting is usually used for weight loss as it leads to calorie restriction relatively easily. Intermittent fasting can result in you eating fewer calories overall - as long as you don't overcompensate by eating more during the eating phases.
Weight loss: Intermittent fasting is generally very successful when it comes to weight loss. It has been shown to cause weight loss of 3 to 8% over a period of 3 to 24 weeks, which is quite a lot compared to most other weight loss diets (99, 100).
In addition to causing less muscle breakdown than standard calorie restriction, intermittent fasting could even increase your metabolic rate by 3.6% to 14% in the short term (99, 101, 102, 1039.
Other benefits: Intermittent fasting could lower markers of inflammation, blood cholesterol levels, blood triglyceride levels, and blood sugar levels (104, 105, 106, 107).
In addition, intermittent fasting has been associated with an increase in endogenous growth hormone levels, increased insulin sensitivity, improved cellular repair and altered gene expression (108, 109, 110, 111, 112).
Studies conducted with animals also suggest that intermittent fasting may help support the growth of new brain cells, extend lifespan and protect against Alzheimer's disease and cancer (113, 114, 115, 116).
The downsides: Although intermittent fasting is safe and harmless for well-nourished and healthy people, it is not for everyone. Some studies also suggest that it is not as beneficial for women as it is for men (117, 118).
In addition, some people should avoid fasting. These include people who are susceptible to a drop in blood sugar levels, pregnant and breastfeeding women, teenagers, children and people who are malnourished, underweight or suffer from nutrient deficiencies.
Summary: Intermittent fasting allows your body to cycle between fasting and eating. Intermittent fasting is effective for weight loss and has been linked to numerous health benefits.
Conclusion
There is no perfect weight loss diet. Different diets work for different people and you should choose the diet that best suits your lifestyle and preferences.
The best diet is the one that you will stick to in the long run.
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