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How to Repair Your Metabolism After Crash and Yo-Yo Dieting

When your metabolism has slowed down after a crash diet or yo-yo dieting, here's what you can do to repair it.
How to Repair Your Metabolism After Crash and Yo-Yo Dieting
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Many people look for a quick fix when it comes to losing weight. It may come as a surprise to learn, however, that “crash” diets and fad diets – like the “very-low-calorie diet” (VLCD) or the HCG 600-calorie-a-day diet – make weight loss even more difficult in the long run. The reason? Metabolism!

After a crash diet, you’re likely to regain the lost weight – and even weigh more than ever – as part of a cycle of yo-yo dieting. Ultimately, crash diets and yo-yo dieting can cause a long-term slowdown in metabolism.

Why and how do crash and yo-yo dieting damage your metabolism? And what can you do to repair a slow metabolism? Let’s take a look at some practical advice.

What is metabolism?

We usually think of "metabolism" in terms of speed: the speed at which we transform food into energy. Metabolism is defined as the complex chemical reactions – occurring at the same time – that take place in the body to convert food into energy.

Your metabolism relies on three factors:

  • Basal/Resting Metabolic Rate (BMR/RMR): About 60 percent of your overall metabolism is determined by your BMR/RMR, the rate at which you burn energy/calories to support essential bodily functions like breathing, circulation, and your brain and organ function. Genetics, age, body composition, diet, and conditions like hypothyroidism also affect your BMR/RMR.
  • Active Energy Expenditure (AEE): About 25 percent of your metabolism is determined by your AEE, which includes both planned exercise and Non-Exercise Activity Thermogenesis, also known as NEAT. NEAT describes the reflexive, involuntary, and non-exercise movements you make throughout the day, i.e., fidgeting, jiggling your foot, standing, walking around, and maintaining good posture.
  • Thermic Effect of Food (TEF): About 15 percent of your metabolism is determined by the thermic effect of the food you eat. The thermic effect is the energy required to break down food and convert it into energy. Protein requires about 20 to 30 percent of its calories for conversion; carbohydrates and fats require around 5 to 15 percent.

What are the signs and symptoms of a slowed-down metabolism?

The most obvious signs of a damaged, slow metabolism are weight gain, weight loss plateaus, and difficulty losing weight — even on a low-calorie diet with exercise. Many other signs and symptoms of a slow metabolism mirror those of hypothyroidism. These include constipation, ongoing fatigue, brain fog, irritability, mood changes, erratic or absent menstrual periods, muscle loss, poor immunity against infection, and sleep disturbances. In addition, some people with a slow metabolism have digestive symptoms such as feelings of intense hunger, heartburn, gas, acid reflux, bloating, and diarrhea.

Some of the risk factors for a sluggish metabolism include:

  • One or more episodes of rapid weight loss (“crash diets”)
  • A history of weight loss followed by a regain of weight (yo-yo dieting)
  • A diagnosis of hypothyroidism
  • A previous eating disorder

How does crash dieting or yo-yo dieting cause weight gain and slow your metabolic rate?

Crash dieting triggers the body to go into starvation mode. Your body protects itself by becoming extremely efficient at absorbing more calories from food. At the same time, your body also deliberately conserves stored energy and burns less of it. It’s a double whammy that results in a slowed metabolism.

When you crash diet, other mechanisms are triggered that make it more likely your metabolism will slow, and you'll regain the weight. For example, with less energy intake, physical activity levels usually drop.

Crash dieting also negatively affects your thyroid function. Specifically, it reduces T3 levels, can trigger or worsen hypothyroidism, and further slow your metabolism.

Other hormones are also affected by rapid weight loss. During and after crash dieting, your stress hormone cortisol increases, creating inflammation, slowing your metabolism, and making your body more effective at storing fat. Rapid weight loss can also cause a leptin drop, -- the hormone that makes you feel full -- or make you resistant to leptin. When you have low leptin or leptin resistance, you feel hungrier and are likely to eat more. Crash dieting can also increase ghrelin levels, the hunger hormone, making you feel hungrier.

Ultimately, researchers have discovered that a crash diet reduces your metabolism far more than slower weight loss. And, after a crash diet, your metabolism stays sluggish, sometimes for years…even if you regain the weight.

How can you fix a broken metabolism after crash diets and yo-yo dieting?

The tendency for the metabolism to stay low after a crash diet and trigger rebound weight gain often leads to weight cycling, or what is known as "yo-yo dieting." When you're yo-yo dieting, you create a calorie deficit and lose weight rapidly, followed by a drop in your metabolic rate. You’ll discover that it’s easier to regain weight, even after cutting daily calories. You regain the weight, and with a reduced metabolic rate, you'll need to reduce calorie intake even more to lose weight gain. It’s a vicious cycle!

To break the cycle, you need to focus on practical ways you can help increase the speed of your metabolism and restore it to a healthier state. Here are some of the best ways to get your metabolism back on track.


Optimize your thyroid function

Because crash and yo-yo dieting can trigger hypothyroidism, a thorough thyroid evaluation is essential to your metabolic health. This can pinpoint a previously undiagnosed case of hypothyroidism or identify the less-than-optimal treatment for your current hypothyroidism. It’s helpful to start with a thyroid blood test panel. Ensure the panel includes Thyroid Stimulating Hormone (TSH) and Free T4, Free T3, and Thyroid Peroxidase (TPO) Antibodies. The results will help you understand how your thyroid functions and if it may negatively affect your metabolism. If you are hypothyroid, you’ll need to work with a knowledgeable doctor to optimize your thyroid hormone replacement treatment to support a healthy metabolism and weight loss.

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Eat a healthy, nutrient-dense, gut-friendly diet

After a crash diet or yo-yo diet cycle, you must focus on eating the healthiest, most nutrient-dense diet you can. This means choosing organic, pesticide-free, whole foods as much as possible and avoiding processed foods. Your emphasis should be on fruits and vegetables, healthy fats, good proteins (like fish and grass-fed meats), and anti-inflammatory fermented foods.

You should also pay attention to your gut health. A healthy gut can more efficiently digest and store food, burn energy when needed, and eliminate waste. For more detailed guidelines, download the free Paloma guide, How To Maintain A Healthy Gut.

You may also want to incorporate more spicy foods into your daily diet. Capsaicin, a key ingredient found in some spicy foods like peppers, has been shown to boost metabolism.

If you need help optimizing your diet for maximum metabolic and health impact, consider working with one of Paloma’s thyroid nutritionists. They can help you determine your nutritional status and develop a diet plan focusing on eating nutrient-dense foods to heal your gut, repair your metabolism, and support your thyroid health.

Increase your protein intake

Many experts agree that increasing your protein can help your metabolism. You burn more calories when you eat protein compared to carbohydrates or fat. One study found that increasing dietary protein to 30 percent of your total food intake, without any increase in carbohydrates, resulted in eating around 400 fewer calories per day. The study participants did not experience increased hunger and lost weight!

Protein also helps you build muscle, which helps raise your metabolic level.

Various experts recommend eating at least 1 gram of protein per pound of body weight daily to support your metabolism. For reference, the following chart lists the amount of protein in a serving of several protein-rich foods:


Increase your fiber intake

Increasing your fiber intake can help boost metabolism because fiber requires more energy to digest, process, and eliminate. Aim for around 25 grams a day of fiber from foods and fiber supplements. Fiber supplements can help you reach the goal of 25 grams per day.

The following chart shows the fiber content of some popular high-fiber foods and supplements for reference:


Eat the majority of your food earlier in the day

When you eat also has an impact on your metabolism. Most experts agree that eating a protein-rich breakfast helps stoke and maintain metabolism and promote fat-burning throughout the day. You may also consider making dinner your lightest meal of the day. You can also fast from dinner until breakfast. This helps you maintain healthier leptin levels and gives your body time to access stored energy for your nighttime energy needs.

Stay well hydrated

You'll want to ensure you regularly drink water throughout the day. Studies have shown that drinking around half of a liter (16 ounces) of water boosts metabolism by up to 30 percent for around 90 minutes. Drinking 2 liters of water daily increases energy expenditure by nearly 100 calories daily. For an extra boost, make it cold water; it raises metabolism a bit more than water at room temperature.

Drink coffee and tea

Caffeine can help boost metabolism. One study showed that around 100 milligrams of caffeine – what you'd typically get in a small cup of coffee – could increase your BMR/RMR by about 3 to 4 percent. Several servings of caffeine at intervals throughout the day can boost metabolism by as much as 11 percent. Moderation is needed, however. Going overboard on caffeine can increase insulin resistance and blood glucose levels.

There’s also scientific evidence that various teas – including black, green, oolong, and goji – can slightly increase your metabolism and fat burning. Tea also provides additional hydration, which can help aid in weight loss.

Use exercise and strength training to increase muscle mass 

The best activity you can do to help boost your metabolism is building muscle. Increasing your muscle mass with exercise like lifting weights, resistance machines, or Pilates can increase your Basal/Resting Metabolic Rate.

Strength training can also help protect your metabolism following a low-calorie diet. One study found that when following a low-calorie diet, women who did resistance training could lose weight without a decrease in metabolism compared to women who did either aerobic or no exercise at all.

Increase your activity level...carefully

Many metabolism experts recommend avoiding extended periods of intense aerobic exercise because it raises cortisol levels. Elevated cortisol wreaks havoc on your metabolism, increasing insulin and glucose levels and slowing your metabolism. 

If you want to do aerobic exercise, shorter periods of intensity – i.e., high-intensity interval training (HIIT) – offer many benefits of aerobic exercise with less risk of raising cortisol.

You can also increase your metabolism by increasing your NEAT. As a starting point, it can be helpful to build regular periods of standing and walking throughout the day.

Get enough sleep

Getting enough sleep is essential for your metabolism. Experts say that 7 to 9 hours per night should be your objective. "Short sleep" of less than 7 hours contributes to a long list of hormonal changes, including blood sugar and cortisol increases. Short sleep reduces the satiety hormone leptin levels, increases the hunger hormone ghrelin, and increases your risk of insulin resistance. One study found that just five days of short sleep caused an increase in food intake, leading to weight gain. Short sleep also reduces your ability to lose fat. Researchers found that dieters who got only 5.5 hours of sleep over two weeks reduced their fat loss by 55 percent!

Manage your stress

Active stress management is an integral part of transforming a slow metabolism. Unmanaged stress raises cortisol levels, negatively affecting glucose, insulin, and metabolism. Specifically, chronically high cortisol levels promote abdominal fat storage, contributing to insulin resistance and weight gain.

The key to stress management is devoting at least 10 minutes daily to your stress-reducing activity. What you do to manage stress depends on what methods work best for you. Meditation, breathwork, gentle yoga, tai chi, playing a musical instrument, or needlework are all valid stress-reducing activities. (Note: a daily stress management is also good for your thyroid and immune health!) 

Breathe mindfully

The practice of mindful breathwork has two key metabolic benefits. First, diaphragmatic breathing is a natural stress reducer; a few slow, deep belly breaths can reduce cortisol levels.

Specific breathing techniques have also been studied and shown to help raise metabolism. Yoga practices such as left, right, or alternating nostril breathing can increase oxygen intake and raise metabolism by as much as 37 percent. 

A note from Paloma Health

Fixing a sluggish metabolism in part depends on having optimal thyroid function. The Paloma Complete Thyroid Blood Test kit can get you started with easy and affordable thyroid testing. Your at-home thyroid test kit contains everything you need to collect and test your Thyroid Stimulating Hormone (TSH), Free T4, Free T3, and Thyroid Peroxidase (TPO) antibodies. You'll also have the option to add on reverse T3 and vitamin D tests. New and veteran hypothyroidism patients can then schedule a virtual visit with one of Paloma’s top thyroid doctors to review lab results and determine the best treatment plan to restore optimal thyroid function.

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Mary Shomon

Patient Advocate

Mary Shomon is an internationally-recognized writer, award-winning patient advocate, health coach, and activist, and the New York Times bestselling author of 15 books on health and wellness, including the Thyroid Diet Revolution and Living Well With Hypothyroidism. On social media, Mary empowers and informs a community of more than a quarter million patients who have thyroid and hormonal health challenges.

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