Amanda Pasko holds a Master’s in Nutritional Epidemiology from the Harvard T.H. Chan School of Public Health and a Master’s in Nutrition from the UNC Gillings School of Global Public Health. To her, it is rewarding to help others reach their goals.
How does the metabolic diet plan 13-day eating plan measure up as a weight loss plan? Can it help you lose weight as advertised, or is it just another popular fad diet that causes more harm than good?
When it comes to finding the best diets for weight loss, it’s always easier said than done. With dozens of eating plans that all claim to be the best fat loss diet available, determining what will work for you can be a headache, particularly as most of us don’t have the time or resources to try every diet that’s out there just to find the perfect one.
To help you narrow down the list of potential weight loss diet plans, we’re going to break down the 13-day metabolic diet plan and tell you if it’s worth your time or not.
Also known as the 13-day diet, 13-day metabolism diet, Copenhagen diet, or the Royal Danish Hospital Diet, this is a 13-day eating plan that promises to help people lose up to 22 lbs (approximately 10 kg) in just under two weeks.
For anyone who wants to better understand this meal plan, here are some things you should keep in mind, as well as some rules that should be followed:
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As previously stated, this metabolic weight loss diet plan is for a total of 13 days. However, we won’t be listing all the meals for 13 days. Instead, we’ll give you a two-day sample of the most popular metabolic diet plan 13-day variations. This will help paint a picture of what your daily meals would look like:
As you can see, these meals are quite small and the servings aren’t nearly enough to keep a grown adult, male or female, full.
According to the Dietary Guidelines for Americans 2020 – 2025, the estimated calorie needs range from 1,600 to 2,400 calories per day for females and 2,000 to 3,000 calories per day for males (1).
Taking this into consideration, it can be seen that the metabolic diet plan 13-day meals are far below what’s considered healthy and fulfilling.
No, it’s not. Despite what this eating plan claims, it won’t help you lose almost 22 pounds in 13 days. Here are 2 main reasons why this diet won’t work:
This is basically a starvation diet that will potentially only lead to the loss of water weight and not actual fat. The hard truth is that sustainable 2-week weight loss is somewhere between 2 to 4 pounds. Any diet that promises anything more than this is a fad diet that should be ignored and never attempted.
In addition to its claims for weight loss being absolutely not based on scientific fact, this diet can actually slow down your metabolism instead of revving it up as it promises. Research has shown that severely restricting your calorie intake can slow down your metabolic rate, which means that your body ends up burning calories more slowly than it already was (2, 3, 4). When your metabolism slows down, this means that most of the food you consume doesn’t get turned into energy and used up but gets stored as fat in the body, which leads to fat and weight gain.
It’s no secret that you can lose weight without necessarily having to exercise. In fact, research has shown that an energy deficit, specifically one that is tailored to the individual, is one of the most important factors in weight loss (5). Basically, as long as you eat following a healthy and nutritionally balanced calorie deficit, the pounds will fall off (6).
However, even while losing weight through diet alone is a possibility, studies have shown that a combination of a good and healthy calorie deficit diet plus exercise is one of the best ways to lose weight (7).
The CDC recommends that adults need (8)
This is the bare minimum every adult needs to do to lead a healthy life, regardless of their weight goals. They also add that if you’re looking to shed some weight, then adjusting your diet and perhaps doing more than the recommended amounts above can help you reach your goals (8).
To summarize, this diet will fail to give you the promised weight loss results because:
Read more: 24 Weight Loss Smoothies, 2 Diet Plans, and 5 Belly Fat Smoothie Secrets
A healthy 13-day diet that combines both exercise and calorie deficit meals can help you lose approximately 2 to 4 pounds. This is in accordance with the Centers for Disease Control and Prevention guidelines that state that healthy and sustainable weight loss generally means a loss of 1 to 2 pounds a week (9).
This is another fad diet that promises to help you lose a large amount of weight by tricking or confusing your metabolism. The diet takes tips from the 5:2 intermittent diet plan where it alternates between high-calorie and low-calorie days.
However, unlike the 5:2 diet that calls for no more than 500-600 calories for women and 600-800 calories for men on fasting days, this confusion meal plan states that on low-intake days, you shouldn’t consume more than 1,200 calories, and on high-intake days, you can consume 2,000 calories or more if you so choose.
Proponents of this meal plan claim that by switching or cycling between high- and low-calorie intakes, your metabolism will be forced to work harder, thereby burning more calories and resulting in weight loss.
But can this diet improve your metabolic rate and boost weight loss? The answer seemingly depends on who you ask as research on the notion of calorie cycling varies.
For example, in 2014, a study by the International Journal of Preventive Medicine showed that calorie cycling, like the one followed by the metabolic confusion meal plan, could have positive results (10).
Researchers took 74 subjects and divided them into two groups: one group only consumed 1,200 calories per day, while the other had their calories restricted for 11 days followed by three (3) days of unrestricted food energy intake.
However, it’s important to note that despite all these positive changes, their metabolic rate remained the same (10).
Despite these promising results in the 2014 study, a 2018 study yielded quite different results (11). This 4-year long study followed 100 participants who were divided into three (3) groups
At the end of the study, researchers found no significant differences in weight loss between people who followed a calorie-shifting diet and those who adhered to traditional calorie restriction (11).
Due to research on calorie cycling differing significantly, we suggest that you should stick to the 5:2 diet and follow its guidelines instead of following a metabolic confusion diet for weight loss. Research on weight loss using the 5:2 diet has remained consistent in demonstrating that it can help with fat loss, weight loss, and general weight management (11, 12).
Check out our other article on fasting for 3 days to see if this is a viable weight loss and metabolism-boosting option for you.
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This meal plan is essentially the same as the metabolic diet plan for 13 days. However, instead of promising a loss of 20 plus pounds in less than 2 weeks, it promises a loss of 20 pounds in 28 days.
It also calls for the elimination of foods such as wheat, corn, dairy, soy, refined sugar, and caffeine. While removing refined sugar is ultimately good for your health (13), removing the rest of these foods can cause more harm than good.
Research has shown that removing entire food groups from your diet or different foods from a normal diet can lead to nutritional deficiencies in both healthy subjects and people suffering from allergies and other health issues (14, 15, 16).
Read more: Your Guide To The 7-Day Protein Diet Plan for Weight Loss
As shown above, this diet isn’t the answer to getting a fast metabolism. However, not all hope is lost. As metabolism plays a significant role in weight loss and gain, learning how to increase it can help you burn calories faster.
Some natural ways to boost your metabolism include drinking more water, working out more, not skipping meals, not severely restricting your diet, and eating foods that will boost your metabolism.
No, you can’t lose belly fat in just 13 days. As with any other fat in the body, losing belly fat takes time, patience, exercise, and a healthy calorie deficit diet.
If you have an endomorph body type, check out our article on the endomorph meal plan to learn the best dietary tips to help you reach your ideal weight goals.
No, you can’t. If you want to lose 20 lbs, it’s best to increase your timeline to two and a half to five months and aim for a weight loss rate of 1 to 2 pounds per week.
Some foods that can boost your metabolism include:
Yes, coffee is allowed on the fast metabolism diet. However, as demonstrated above, this diet isn’t the best or healthiest for weight loss, so we recommend that you don’t indulge in it. However, you can still drink coffee as part of a healthy diet as research has shown that catechins – which are found in both coffee and tea – have some metabolism-boosting benefits (17, 18).
No, you shouldn’t. While we agree that weight loss is difficult and understand the desire to see fast results, we can’t recommend this eating plan to you in good faith. Not only is this a fad diet that promises unachievable results, it’s also extremely low in calories and lacking in nutrients and could land you in hospital.
If you’re looking to change your diet to lose weight, please consult your doctor or dietitian to help determine what’s the best diet for weight loss for you – a diet that won’t jeopardize your health.
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