Is it common to lose weight in high-protein and low-carb diets?: Understanding the science and expectations

October 18, 2025 •

4 min read

Research shows that higher protein consumption can significantly increase feelings of fullness, which often leads to a reduction in overall calorie intake. This is a key reason why it is common to lose weight in high-protein and low-carb diets, especially in the initial stages.

Quick Summary

This article explores the mechanisms behind weight loss on high-protein, low-carb diets, examining the roles of increased satiety, initial water weight loss, and fat utilization. It covers both the common, rapid short-term results and the complexities of long-term sustainability.

Key Points

Initial Weight Loss: The early weight loss is common and significant, driven largely by the loss of water weight associated with depleting glycogen stores.
Increased Satiety: A high-protein intake promotes feelings of fullness, which helps reduce overall calorie consumption and manage appetite.
Metabolic Shift: With restricted carbs, the body shifts to burning stored fat for energy, a process that can accelerate weight loss.
Long-Term Limitations: While effective initially, studies show the weight loss advantage over other diets often diminishes after 6-12 months, with long-term adherence being a major challenge.
Calorie Deficit is Key: Ultimately, weight loss is contingent on a calorie deficit, regardless of the macronutrient strategy employed.
Potential Health Risks: High-protein, low-carb diets carry risks such as nutrient deficiencies, increased saturated fat intake, and potential kidney strain, requiring careful planning.

How High-Protein, Low-Carb Diets Promote Weight Loss

High-protein, low-carb (HPLCD) diets have gained immense popularity for their potential to trigger rapid weight loss. This effectiveness stems from several key physiological and behavioral changes that occur when you alter your macronutrient intake.

Increased Satiety from Protein

Protein is widely known as the most satiating macronutrient, meaning it helps you feel full and satisfied for longer periods. This effect has a significant impact on weight management by naturally reducing overall calorie consumption without consciously counting them. When your hunger is consistently managed, you are less likely to overeat or succumb to cravings for high-calorie, low-nutrient foods, particularly refined carbohydrates and sugars.

The Role of Initial Water Weight Loss

In the first few weeks of starting an HPLCD, many individuals experience a noticeable and often motivating drop in weight. This is largely due to the reduction of carbohydrate intake, which causes the body to deplete its glycogen stores. Glycogen is a stored form of glucose that holds onto a significant amount of water. As these stores are used up, the body releases this water, leading to a temporary, yet substantial, decrease in body weight. While this is not fat loss, it can provide a psychological boost that helps with adherence.

Shifting the Body's Fuel Source

With a restricted carbohydrate supply, the body is forced to find an alternative fuel source. This process, often leading to a metabolic state called ketosis in very low-carb diets like keto, involves the body breaking down stored fat into ketones for energy. By shifting the primary fuel source from carbohydrates to fat, the body can more effectively burn its fat reserves.

Short-Term vs. Long-Term Results

Numerous studies confirm that HPLCDs can be highly effective for short-term weight loss. A 2006 meta-analysis found greater weight loss for HPLCDs compared to low-fat diets at six months, but this difference was often negligible after a year. This suggests that while the initial push is strong, the long-term outcomes are less distinct when compared to other calorie-restricted diets. The primary driver for long-term weight loss is maintaining a consistent calorie deficit, regardless of macronutrient distribution.

Challenges with Long-Term Adherence

One of the main challenges for many people is sustaining an HPLCD over the long term. These diets can be restrictive and may limit the intake of fruits, vegetables, and whole grains, which are essential for nutritional balance and fiber intake. The risk of poor compliance is high, which can lead to regaining weight once the diet is stopped. Successful and lasting weight loss typically requires a sustainable lifestyle change rather than a temporary diet.

Potential Health Considerations and Risks

While effective for weight loss, HPLCDs are not without risks, and certain individuals should be cautious or avoid them entirely. It's always best to consult a healthcare professional before starting a new diet.

Nutrient Deficiencies: Restricting entire food groups, such as fruits and certain vegetables, can lead to deficiencies in important nutrients like fiber, vitamins, and minerals.
Increased Saturated Fat Intake: Many protein sources, especially red meat and certain dairy products, can be high in saturated fat. Overconsumption may increase cholesterol levels and heart disease risk, though some studies show mixed results. Choosing lean protein sources is crucial.
Kidney Strain: High protein intake can increase the acid load on the kidneys, which could be problematic for individuals with pre-existing kidney conditions or predispositions.
Constipation: A diet low in fiber-rich carbohydrates can disrupt normal bowel function and lead to constipation.

Practical Comparison: High-Protein, Low-Carb vs. Balanced Diet


Feature	High-Protein, Low-Carb Diet	Balanced, Calorie-Restricted Diet
Short-Term Weight Loss	Often rapid, partly due to water loss.	Slower but steadier pace.
Satiety	High protein boosts fullness, reducing overall intake.	Satiety is controlled by fiber and balanced macros.
Metabolic Shift	Encourages fat burning through ketosis with very low carbs.	Maintains body's typical use of glucose for fuel.
Long-Term Sustainability	Can be difficult to maintain due to restrictions.	More sustainable due to flexibility and food variety.
Nutrient Gaps	Higher risk of deficiencies in fiber and certain vitamins.	Lower risk due to inclusion of all food groups.
Health Risks	Potential for kidney strain and increased saturated fat intake.	Risks are minimal if balanced and nutrient-dense.
Adherence	High dropout rates observed in long-term studies.	Better adherence linked to flexibility and enjoyment.

Conclusion

So, is it common to lose weight in high-protein and low-carb diets? The answer is a clear yes, particularly in the short term. These diets leverage the satiating effect of protein and the metabolic shift that occurs when carbohydrates are restricted, leading to significant initial results. However, sustained weight loss ultimately depends on creating and maintaining a calorie deficit, and the long-term effectiveness of this approach often plateaus and proves challenging for many to adhere to. For lasting success and overall health, a sustainable and balanced approach that ensures all nutritional needs are met is often more beneficial.

It is crucial to consider the potential risks and to consult with a healthcare professional before making significant dietary changes, especially if you have pre-existing health conditions. Focusing on high-quality, whole foods and combining proper nutrition with regular physical activity is the most reliable path to achieving and maintaining a healthy weight. For further reading on the long-term outcomes and risks, a review from PubMed provides additional insights.

Frequently Asked Questions

The rapid initial weight loss is primarily due to the body depleting its glycogen reserves, which hold a large amount of water. As the body uses this stored glycogen for energy, it releases the associated water, causing a quick drop on the scale.

Not necessarily. While they can be very effective in the short term, studies show that after about 6 to 12 months, the weight loss results are often similar to those achieved with other calorie-restricted diets. Long-term success is more about consistency and overall calorie balance.

The most important factor is maintaining a calorie deficit, meaning you burn more calories than you consume. The high protein and low carbs help achieve this by increasing satiety and reducing overall intake, but the deficit is what drives the loss.

Yes, potential risks include nutrient deficiencies from restricting certain food groups, an increased intake of saturated fat if not carefully planned, and potential strain on the kidneys, especially for individuals with pre-existing conditions.

To avoid nutrient gaps, focus on consuming a wide variety of nutrient-dense, low-carb foods such as non-starchy vegetables (e.g., broccoli, spinach), lean protein sources (e.g., chicken, fish), healthy fats (e.g., avocados, nuts), and lower-carb fruits like berries.

Exercise is highly recommended. Combining a proper nutrition plan with regular physical activity, especially resistance training, helps maximize fat loss while preserving or building muscle mass, which boosts metabolism.

People with kidney problems or a history of eating disorders should be particularly cautious or avoid this diet entirely. Pregnant or breastfeeding women also have unique nutritional needs that may not be met by this restrictive approach.