The 5 worst slow metabolism causes (And How to Fix Them)

Your metabolism isn’t just about genetics—it’s shaped by daily habits, diet, and lifestyle choices. According to Dr. Michael Greger, author of How Not to Die, a plant-based, whole-food diet and active lifestyle are key to optimizing metabolism and long-term health.

But what if your metabolism isn’t working as efficiently as it should? Many people unknowingly engage in habits that slow their metabolic rate, making weight loss and energy management harder.

These are five common slow metabolism causes and how to fix them naturally.

1. Eating Too Many Processed Foods

Refined carbs, added sugars, and ultra-processed foods spike blood sugar and increase fat storage, slowing metabolism over time. Dr. Greger emphasizes whole plant-based foods over processed options for optimal metabolic health.

How It Affects Your Metabolism:

• Processed foods lack fiber, leading to blood sugar spikes and crashes.

• Artificial ingredients can disrupt gut bacteria, which play a role in metabolism.

• Studies show a whole-food, plant-based diet increases calorie burn due to the thermic effect of food (TEF).

How to Fix It:

Choose whole, fiber-rich foods like beans, vegetables, and whole grains. Swap sugary snacks for fruits and nuts to keep blood sugar stable.

Reduce or eliminate refined grains, added sugars, and artificial additives.

2. Not Getting Enough Plant-Based Protein

Protein plays a major role in muscle maintenance and metabolism. Dr. Greger encourages plant-based proteins over animal proteins due to their health benefits and impact on longevity.

How It Affects Your Metabolism:

• Protein requires more energy to digest than fats or carbs, increasing calorie burn.

• Low protein intake can lead to muscle loss, slowing your resting metabolic rate.

• Plant proteins like legumes and soy are linked to better metabolic health compared to processed meats.

How to Fix It:

Incorporate lentils, chickpeas, tofu, tempeh, and quinoa into meals. Start the day with a high-protein plant-based breakfast (oats with nuts, tofu scramble, or a smoothie). Avoid relying on highly processed vegan protein bars or shakes.

3. Sitting Too Much and Not Moving Enough

A sedentary lifestyle is one of the biggest metabolism killers. Even if you work out, sitting for long hours can slow circulation, increase fat storage, and reduce calorie burn.

How It Affects Your Metabolism:

• Sitting too long reduces fat-burning enzyme activity in the body.

• Low movement leads to insulin resistance and weight gain.

• Non-Exercise Activity Thermogenesis (NEAT)—small movements like walking, fidgeting, and standing—accounts for a significant portion of daily calorie burn.

How to Fix It:

Stand up and move every 30 minutes—even small movements increase calorie burn. Take walk breaks after meals to regulate blood sugar. Use a standing desk or treadmill desk if possible.

4. Not Sleeping Enough (or Sleeping Poorly)

Poor sleep is one of the most underrated causes of metabolic slowdown. Dr. Greger highlights how chronic sleep deprivation increases cortisol, leading to weight gain, sugar cravings, and reduced energy expenditure.

How It Affects Your Metabolism:

• Sleep deprivation increases ghrelin (hunger hormone) and decreases leptin (satiety hormone), making you hungrier.

• Cortisol spikes from poor sleep encourage fat storage, especially in the belly.

• A well-rested body burns more calories at rest than a sleep-deprived one.

How to Fix It:

Aim for 7-9 hours of high-quality sleep per night. Reduce screen time before bed to avoid blue light exposure. Create a nighttime routine with calming activities (reading, meditation, stretching).

5. Not Eating Enough Whole, Fiber-Rich Foods

Fiber is essential for gut health, satiety, and metabolism. Dr. Greger emphasizes fiber as a key nutrient for weight management and overall health. Yet, most people don’t get enough of it.

How It Affects Your Metabolism:

• Fiber slows digestion, keeping you full longer and preventing overeating.

• A healthy gut microbiome—fed by fiber—enhances metabolism.

• Studies show higher fiber intake is linked to lower body fat and improved insulin sensitivity.
  

How to Fix It:

Increase legumes, whole grains, vegetables, and fruits in your diet. Swap processed snacks for fiber-rich alternatives like nuts, seeds, and whole fruit. Drink enough water to help fiber do its job properly.

Final Thoughts: Slow Metabolism Causes Aren't Permanent

Your metabolism isn’t set in stone—your daily choices impact how efficiently your body burns calories. Dr. Greger’s research supports plant-based, whole-food nutrition as the foundation of a strong metabolism.

By avoiding processed foods, increasing movement, prioritizing sleep, and eating fiber-rich, plant-based meals, you can naturally improve your metabolism and overall health.

Simple Takeaways:

Eat whole, plant-based foods with fiber and protein. Move more throughout the day—not just during workouts. Prioritize good sleep to avoid metabolic slowdowns. Ditch processed foods and added sugars for better energy and fat burning.

Have you noticed changes in your metabolism with diet and lifestyle tweaks? Let us know in the comments!