The ketogenic diet, or keto, has gained popularity as a low-carb approach to eating that can lead to weight loss and improved health. However, weight loss isn’t as simple as just increasing your fat intake and limiting carbs. To reap the benefits of the keto diet, it must be implemented correctly. While many people have lost a considerable amount of weight on keto, some have difficulty losing weight or experience unexpected weight gain. It's important to remember that weight loss isn’t an indicator of health. You have to get healthy to lose weight, not lose weight to get healthy. There are many hormonal and metabolic factors that may be causing weight gain despite limiting your carbohydrate intake.
It’s difficult to keep your weight stable and it can seem alarming when it tends to shift up or down by a few pounds. This is completely normal and can be a result of many factors that affect your body, including what you eat or drink and how much exercise you get on any given day. Early morning versus late evening for example - which means a person might weigh 170 at 8 pm but 175 at 10 am the next morning. Weight fluctuation is a normal but often misunderstood phenomenon. When you realize you’ve gained 5 pounds in a day, your first instinct may be to panic.
It’s impossible to gain five pounds of fat in a day - to do this, you’d have to eat over 20,000 calories in 24 hours. When your scale shows a higher number, it’s usually water weight.
Let's explore the potential causes of weight gain and water retention on keto and learn natural ways to help reduce fluid retention while following a low-carb diet.
Here are eight causes of weight gain on keto and the solutions to achieve a healthy weight.
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Reasons for Weight Gain on Keto
Not Staying in Ketosis
One of the most common reasons for weight gain on keto is an inconsistent carb intake that causes your metabolism to flip-flop between fat-burning and using sugars as the primary energy source. Keto success depends on limiting carb intake to keep insulin low, which triggers ketosis and primes your metabolism to break down fats. Cheat days on keto aren’t a great idea and can quickly derail your weight loss efforts. Whenever you consume too many carbs, your insulin levels will spike, which inhibits fat burning and stimulates fat storage. And, what’s more, it typically takes your body a few days to restart ketosis after consuming too many carbohydrates, which slows down keto-adaptation and can lead to weight gain. To achieve consistent weight loss, it’s crucial to limit your net carb count to no more than 20 to 50 grams per day and consume plenty of healthy fats and moderate amounts of protein.
Stress
Stress is an often overlooked factor when it comes to weight gain. When you experience stress, your adrenal glands release cortisol, a hormone that regulates metabolic processes to support the body’s energy needs during stressful periods. While cortisol plays a vital role in your body’s stress response, prolonged stress can lead to chronically elevated cortisol, which has been found to contribute to weight gain. Evidence published in Current Obesity Reports suggests that cortisol stimulates fat storage, especially around the abdomen. This explains why prolonged stress can cause an adrenal body type characterized by unexplained weight gain and belly fat. A healthy lifestyle, adequate sleep, regular exercise, and relaxation techniques such as deep breathing and long walks can calm the nervous system and may help counteract cortisol’s weight-gain effects.
Slow Metabolism
Individuals with a slow metabolism burn fewer calories than those with a higher metabolic rate. There are many reasons for a slow metabolism, including menopause, hypothyroidism, genetic predisposition, hormone imbalances, and frequent dieting. If you suspect you have a slow metabolism, monitoring your fat intake on keto is essential. Fat contains almost twice as many calories as carbs, and it’s easy to consume excessive amounts of calories on a high-fat diet, which can quickly lead to weight gain. Boosting your metabolism doesn’t really work, but you can improve your metabolic flexibility, a measure of how quickly your body adapts to using fat instead of sugar as a primary fuel source. Combining keto with intermittent fasting, a meal schedule that cycles between fasting periods and periods of eating, forces your metabolism to burn stored body fat for energy. This stimulates increased production of fat-oxidizing enzymes in the liver, enhancing your metabolism’s ability to utilize body fat as a primary fuel source.
Not Consuming a Nutrient-Dense Diet
Achieving healthy and long-lasting weight loss with keto requires more than limiting carbs and increasing fats. There are many fast foods, junk foods, and processed foods that are low in carbs and high in fat, but these foods won’t help you lose weight and may, in fact, cause weight gain. Research published in Clinical Nutrition confirms that a diet high in processed foods is linked to overeating, nutritional deficiencies, and metabolic imbalances, which can significantly increase the risk of obesity. To promote healthy weight loss, it’s vital to follow a nutrient-dense Healthy Keto® diet that focuses on minimally processed keto-approved whole foods, including grass-fed beef, wild-caught fish and game meats, seafood, high-fat dairy, and organic vegetables.
Alcohol
Although pure alcohol has zero carbs, drinking alcoholic beverages can quickly lead to weight gain. Because alcohol is a toxic compound, the liver prioritizes alcohol detoxification over other metabolic processes, including fat burning. In addition, most alcoholic beverages are high in carbs and often mixed with sugary soft drinks or fruit juices. Even small amounts of alcohol can stop weight loss and ketosis, and it can take 48 to 72 hours to restart fat-burning after drinking. Alcohol is a common reason for weight gain on keto, and it’s best to minimize or avoid alcohol as much as possible to maintain ketosis and promote metabolic health.
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Imbalanced Intestinal Microflora
Although it may not seem obvious, your intestinal microflora can significantly impact your weight status. An imbalance or disruption in the composition of the gut microflora, also known as dysbiosis, has been found to disrupt fat metabolism, increase the risk of insulin resistance, and may cause low-grade inflammation, all of which have been linked to weight gain. According to a study published in Microorganisms, “A shift from the healthy symbiosis between the microbiota and the host to persistent dysbiosis may contribute to excess fat deposition. You can promote a diverse intestinal microflora by consuming pre- and probiotic-rich foods such as garlic, onions, asparagus, artichokes, kefir, sauerkraut, and kimchi.
Lack of Physical Activity
Regular exercise is important for metabolic health, especially if you are gaining weight despite following a healthy diet low in carbs. Muscles are more metabolically active and burn more calories than most other tissues, even at rest. Building muscle mass can counteract a slow metabolism and may prevent weight gain. Regularly including high-intensity interval training in your keto lifestyle can help you lose fat and gain muscle simultaneously.
Underlying Health Issues
Underlying health issues can significantly impact weight, fat distribution, and body composition. Categorizing different body types based on potential underlying health problems is very helpful in finding effective solutions that improve well-being and support healthy weight loss. Hypothyroidism, polycystic ovarian syndrome (PCOS), Cushing’s syndrome, depression and hyperinsulinemia (high insulin levels) are medical issues that can cause weight gain and make it difficult to lose weight. These conditions can be ruled out by your doctor through a series of tests. If you have one of the conditions listed above, don’t despair. Through proper management, including medication if necessary and lifestyle and dietary modifications, you can achieve and maintain healthy weight loss.
Understanding Water Weight
Water weight, also known as fluid retention, refers to excess fluid that accumulates in your body’s tissues, organs, and cellular spaces.
Causes of Fluid Retention on Keto
When following low-carb diets such as the ketogenic diet, your body undergoes metabolic shifts that directly impact how water is retained and eliminated. During ketosis, carbohydrate intake is drastically reduced. This depletes glycogen, the body’s stored form of glucose, which is tightly bound to water. Approximately three grams of water are bound to every gram of glycogen. In the early stages of keto, glycogen stores are depleted, and the associated water is released, which is why many people experience rapid initial weight loss. However, water weight can return just as quickly under certain conditions. You’re typically not gaining fat when the scale goes up on keto; it’s usually just fluid accumulation. The key is understanding what’s triggering the retention.
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Electrolyte Imbalance
Electrolyte balance, especially the ratio of sodium and potassium, is often overlooked when starting a keto diet. Sodium and potassium regulate fluid balance at the cellular level, with sodium pulling water into tissues and potassium helping to flush excess fluid. Most people eat high amounts of sodium but not enough potassium-rich foods, such as leafy green vegetables, avocados, and salmon, to help maintain equilibrium. Ideally, the body should maintain a 4:1 ratio of potassium to sodium. Without enough potassium to counterbalance sodium, your kidneys retain water instead of releasing it, leading to water retention and bloating.
Excessive Fiber Intake
Beneficial gut bacteria play a crucial role in digestive functions as they help break down fiber. However, if you aren’t used to eating many vegetables, your gut microbiome may struggle to process a sudden increase in fiber-containing foods, especially when starting a nutritious Healthy Keto® diet. Since soluble and insoluble fiber absorb water in the digestive tract, an abrupt increase in fiber without adequate microbial breakdown can lead to bloating, constipation, and water retention.
Hidden Carbohydrates
Even small amounts of hidden carbohydrates in processed foods, even those labeled low-carb or keto-friendly, can affect water retention. Many packaged foods contain hidden ingredients such as maltodextrin, dextrose, or modified starches that can spike blood sugars and insulin. This disrupts ketosis and triggers glycogenesis, which causes water retention to bind glycogen reserves in muscles and the liver, leading to water weight gain. Furthermore, frequent insulin spikes can deplete vitamin B1, an essential nutrient for fluid balance and carbohydrate metabolism.
Other potential causes of 5 pounds weight gain overnight
- Intense Workout: If you’ve done a particularly intense workout, whether it’s a sprinting session or a spinning class, your body may retain more water than usual after the exercise. You also may be storing more glycogen in your muscles to fuel your workouts if you’ve started a new or more intense workout regimen.
- Alcohol Consumption: Drinking alcohol makes you retain both water and salt through osmosis, which means that alcohol draws more water out from your bloodstream into your tissues.
- Excess Sodium Intake: Excess intake of sodium causes water retention after you eat it. This is because your kidneys retain fluid in an effort to dilute the salt until they can filter it out of your blood.
- Dehydration: Dehydration causes your body to retain excess water, which can lead to 5 pounds of weight gain overnight.
- Food Intolerance or Allergy: If you have a food intolerance or allergy, eating the offending food may result in inflammation in your gastrointestinal tract.
- Menstrual Cycle: Many women notice that they put on 5 pounds right before their period due to bloating caused by their menstrual cycle. If you’re pregnant, it’s perfectly normal to gain 5 pounds overnight. You’re most likely experiencing weight fluctuation and fluid retention due to your hormones.
- Medication Side Effects: If you were recently prescribed any medication, it’s important to take note of its potential side effects.
- Late-Night Eating: Eating late at night may cause weight gain over time due to an increase in body fat, but not in one night.
- Resistance training: Resistance training can cause microscopic tears in muscle tissue.
- Medications: Hunnes and White both note that certain medications can cause your scale weight to increase.
- Sodium: “You may have had a meal loaded with sodium, which could explain why your morning weight is up,” White notes.
- Carbs: Carbs are also a notorious cause of this heart-stopping scale surge.
- Fiber: Fiber is great for you. But if you up your fiber intake too quickly, it might take some time for your body to catch up. “More fiber will turn into a heavier, bulkier, waterier, and more massive bowel movement.
- Menstruation: People who menstruate, listen up.
Strategies to Lose Water Weight on Keto
If you’re dealing with fluid retention after starting keto, there are several ways that you can help your body restore a healthy fluid balance without disrupting your progress.
Support Digestion and Ease into Fiber Intake
Increasing your intake of non-starchy vegetables too quickly can overwhelm digestion, causing fluid retention, bloating, and constipation. To help your body adapt to digesting larger quantities of fiber, start with small amounts of cooked vegetables and gradually add raw, fibrous greens as your digestive system adjusts. Incorporating probiotic-rich, keto-friendly foods, such as raw sauerkraut or other fermented foods can enhance microbial diversity and B vitamin absorption, which supports fluid balance and helps avoid unexpected weight gain from water retention.
Incorporate Natural Diuretics
Certain herbs and foods naturally help the body release excess fluid. Dandelion greens are rich in potassium and support liver function and water release. According to research published in Medicinal Herbs in Primary Care, “Dandelion leaf has diuretic, choleretic, and anti-inflammatory properties.” Garlic, black tea, and parsley are additional herbal options that can promote diuresis, meaning they help increase urine production to reduce excess water retention in the body. Unlike synthetic diuretics, which may deplete minerals, these foods can support fluid release while maintaining nutrient balance. For example, black tea can help eliminate sodium without significantly affecting potassium levels, supporting a healthier fluid balance in those with high sodium levels.
Avoid Processed Foods
Eating processed foods is the most common factor that prevents weight loss success. These foods have little to no nutritional value and often contain hidden ingredients that contribute excess calories from low-quality sources that lead to spikes in insulin, increased appetite, and poor nutrient balance. To help prevent water retention, it’s crucial to avoid processed foods and carefully read labels to identify hidden carbs and harmful ingredients.
Follow Healthy Keto
Following a Healthy Keto eating plan, which emphasizes high-quality, nutritious whole foods is one of the best things you can do to promote fluid balance. Healthy Keto food staples, such as leafy green vegetables, full-fat dairy products, grass-fed beef, and unfortified nutritional yeast, are rich sources of potassium and vitamin B1. This nutritious meal plan also supports blood sugar control, reduces cravings, and helps suppress appetite naturally, which can contribute to better weight management and less water retention.
Practice Intermittent Fasting and Dry Fasting
Intermittent fasting enhances the natural diuretic effects of ketosis by maintaining low insulin levels. Additionally, dry fasting, which involves abstaining from food and water for a short period, usually between 10 and 18 hours, can help remove excess water, promote fat burning, and reduce puffiness from water retention. However, this strategy should only be attempted once you’re fat-adapted and consistently in ketosis.
Other Strategies for Sustainable Weight Loss on Keto
Track Your Food Intake
One of the biggest culprits of weight gain on keto is not tracking your food intake. It’s important to track everything you eat to be sure you’re not overdoing it in any area. You also want to ensure you’re keeping your macros in check. To help you reach your keto intake goals, consider tracking your carb, fat, and protein intake with an app like MyFitnessPal, Cronometer, or Carb Manager.
Manage Calorie Intake
When trying to lose weight, it’s critical to create a calorie deficit. This can be achieved by either reducing the number of calories that you consume or by expending more calories through increased physical activity. If you switch to a keto diet and don’t watch your calorie intake, you’re unlikely to drop pounds. Because many keto-friendly foods, including avocados, olive oil, full-fat dairy and nuts, are high in calories, it’s important not to overdo it. Most people feel more satisfied after eating ketogenic meals and snacks due to the filling effects of fat and protein. However, it’s entirely possible to consume too many calories on a ketogenic diet by eating portions that are too large or by snacking on high-calorie foods throughout the day. Paying attention to portion size, increasing physical activity and snacking in moderation between meals can help create the calorie deficit needed to lose weight.
Adjust Macronutrient Ratios
Even keto-friendly foods can add up to too many carbs per day if you’re not careful. Fats are the most calorically dense macronutrient. Many people think of a keto diet as a free-for-all when it comes to fat, but this isn’t the case. Eating too much protein can actually kick your body out of ketosis. Instead, you should only eat a moderate amount of protein, or about 20% of your daily intake.
Limit Alcohol Consumption
Drinking alcohol can slow down the weight loss process and can even contribute to weight gain if you overdo it. Alcohol intake can impair keto weight loss results in several ways. Cutting it out completely is generally the healthiest option, but you can still get the results you want with a moderate alcohol intake. In other words, when you do drink, keep alcoholic beverage consumption below two servings per day for men or one serving per day for women.
Prioritize Sleep and Stress Management
A lack of sleep has been shown to increase appetite and cravings, making it harder to resist and restrict our intake of unhealthy foods. You can lower stress and improve sleep quality at the same time by adding meditation and/or journaling to your bedtime routine. Chronic stress can drive hunger and greatly reduce your ability to resist cravings. One of the best stress-relieving practices is maximizing sleep quality. A lack of sleep is a major driver of hunger, cravings, and subsequent weight gain. Prioritizing sleep quality is a secret weapon to making any diet easier.
Increase Physical Activity
This is thought to be your body’s natural energy-conserving mechanism, which is triggered whenever food is limited. To counteract this, we must make a conscious effort to move more throughout the day. Regular exercise can help reduce stress levels, boost appetite control, and speed up weight loss. Aerobic activities, such as walking, cycling, and jogging, can help curb your appetite.
Address Underlying Medical Conditions
Certain health conditions make weight loss extremely difficult. Hypothyroidism, Cushing’s syndrome, Polycystic Ovarian Syndrome, and many other conditions can stall weight loss. Certain medications, particularly antidepressants, can cause you to gain weight. That said, regardless of what condition you have or medication you take, it is still possible to improve your health and body composition.
Avoid Severe Calorie Restriction
When we rely on severe calorie restriction, we still lose weight, but more of it will come from muscle mass than we’d like. To break the cycle of weight loss and regain, try aiming for a gentle calorie deficit that promotes a weight loss rate of 1 to 2 pounds per week.
Manage Hunger
Eat the right amount of food. In earlier sections, we emphasized how eating too much fat can cause weight gain on keto, but this doesn’t mean we should severely restrict food consumption. Eat more nutrient-rich foods. In other words, get most of your fat and protein from minimally processed keto-friendly whole foods. Add a protein-rich food to each meal. Protein intake helps suppress hunger and curb cravings.