How Does a Low-Carb Diet Work?
The Low-Carb Diet alters how your body processes energy, shifting from using carbohydrates (glucose) as its primary fuel to relying more on fat (ketones). Here is how it happens:
- Step 1: Reduction in Carbohydrates
- Step 2: Lowered Blood Sugar and Insulin Levels
- Step 3: Fat as an Alternative Fuel Source
Step 1: Reduction in Carbohydrates
When you reduce your intake of carbohydrates, you are cutting back on foods that are quickly converted into glucose (sugar) in the bloodstream.
This includes high-carb foods like bread, pasta, rice, and sugary snacks. In a typical high-carb diet, glucose is the primary energy source.
Step 2: Lowered Blood Sugar and Insulin Levels
As your carb intake decreases, the amount of glucose in your bloodstream lowers, leading to a reduction in the hormone insulin, which is responsible for transporting glucose into your cells to be used as energy or stored as fat.
With fewer carbohydrates, insulin levels remain lower and more stable, reducing insulin resistance, which is the cause of various chronic diseases, from cardiovascular issues to cancer.
Insulin is also a fat-storage hormone. When its levels are high, your body stores fat more easily. Lowering insulin levels encourages the body to release stored fat for energy instead of storing it, which boosts fat melting and weight loss.
Step 3: Fat as an Alternative Fuel Source
With glucose levels dropping and less insulin circulating, your body begins to look for an alternative energy source. The most readily available option is fat, both from the food you eat and from your stored body fat.
Over time, your body becomes fat-adapted, meaning it gets better at burning fat for fuel instead of carbohydrates. This process helps you lose weight because your body consistently uses fat for energy rather than relying on quick bursts of glucose.
The good news is that a large number of studies over the past decades have verified the effectiveness of low-carbohydrate diets.
Does Science Back the Low-Carb Diet?
Yes, various studies have been conducted on different aspects of the Low-Carb Diet and Ketogenic lifestyle, proving its effectiveness in weight loss, blood sugar control, and improved cardiovascular health. Let’s get into the details.
The Benefits of the Low-Carb Diet
Eliminating unnecessary foods (carbohydrates) can significantly affect different parts of our body, from blood sugar and the digestive system to the brain and heart.
Various studies report that the Low-Carb Diet can help manage diabetes, boost weight loss, reduce triglycerides, and increase HDL (good) cholesterol levels [1].
The Low-Carb Diet Can Help Reduce Inflammation
Inflammation is one of the biggest health concerns that can lead to various chronic diseases, from artery constriction to kidney dysfunction.
A 2014 study indicated that following a Low-Carb Diet and minimizing carbohydrate intake in type 2 diabetic patients significantly improved their subclinical inflammatory state [2].
The Low-Carb Diet Can Boost Weight Loss
Various studies show that a Low-Carb Ketogenic Diet can lead to weight loss by activating a metabolic switch to oxidize fats, which can suppress hunger by producing ketone bodies [3] [4].
A 2023 study on the effects of Low-Carb Ketogenic diets on weight loss showed that limiting carbohydrate intake can lead to rapid weight loss (due to water weight loss) at first and sustainable weight loss (fat loss) over time [5].
A 2007 study comparing different low-carb diets over a year indicated that the lowest-carb diet showed better weight loss results [6].
The Low-Carb Diet Can Improve Digestive Health
Different studies have supported the positive impacts of the Low-Carb Ketogenic Diet on metabolic health and lower seizure activities, which are influenced by the gut microbiota [7].
A 2007 study on the effects of nutrition on weight loss and diabetes suggested limiting carbohydrate intake can shift the energy source from glucose and fatty acids to fatty acids and ketones, which can help suppress appetite, boost weight loss, and improve surrogate markers of cardiovascular disease [8].
Learn More: The No-Carb No-Sugar Diet: Everything You Need to Know
The Low-Carb Diet Can Help Manage Blood Sugar Levels
A 2005 study on 10 obese patients with type 2 diabetes indicated that going on the Low-Carbohydrate Diet for 14 days led to reduced energy intake, weight loss, improved 24-hour blood glucose profiles, insulin sensitivity, and hemoglobin A1c, and decreased cholesterol levels and plasma triglyceride [9].
Different studies indicate that carbohydrate restriction is an effective approach to controlling type 2 diabetes and reducing medications, even more effective than other approaches [10] [11].
Controlling blood glucose levels and managing diabetes is one of the best measures you can take to avoid a wide range of chronic health problems, from brain damage and heart attack to different cancers.
The Low-Carb Diet Can Improve Brain Function
Studies on the effects of the Low-Carb Ketogenic Diet on brain function indicate that a ketogenic diet can positively impact neurological disorders by balancing pro- and antioxidant processes and pro-excitatory and inhibitory neurotransmitters, regulating inflammation, or altering the composition of the gut microbiome [12] [13].
The Low-Carb Diet Can Improve Heart Health
Various randomized controlled trials on the effects of low-carb diets report positive impacts of such diets on reducing body weight and improving cardiovascular risk factors [14] [15].
Despite these positive effects, the Low-Carb Diet may lead to temporary side effects in some individuals, especially during the initial adaptation phase.
The Low-Carb Diet Can Improve Autoimmune Conditions
A 2023 study on the effects of low-carb diets on MS reviewed 15 original research articles, including in vitro, preclinical, and clinical studies, and found that Low-Carb Ketogenic diets are safe and feasible for treating MS.
They show potential neuroprotective impacts and positive results on cellular metabolism and disease outcome [16].
A 2022 study on the immune modulatory effects of a Ketogenic Diet in different disease conditions analyzed several scientific records, models, and case histories, including viral infections, cancer, chronic diseases, such as cardiovascular diseases, epilepsy, and numerous other neuro-disorders, and found that a Loe-Carb Ketogenic Diet can positively impact the patient’s condition [17].
Downsides of the Low-Carb Diet
Changing your eating habits and starting the Low-Carb Diet causes your body, especially the digestive system, to go through changes to adapt to the new eating habits.
This initial adaptation phase may cause temporary constipation, diarrhea, low energy levels, nausea, and headaches, which usually fade away after some days, especially if you consume enough water and electrolytes [18] [19] [20].
To avoid these possible side effects and make the most of your low-carbohydrate journey, you need to know what foods to eat and avoid.
Learn More: High-Protein, Low-Carb Breakfast without Eggs: 15 Recipes
Food List of the Low-Carb Diet
If you think you have to make big changes in your eating habits and avoid your favorite foods when you start the Low-Carb stage of the Primal Diet, think again! You are still allowed to consume a wide range of foods. Here are the best low-carb vegetables, fruits, nuts, snacks, alcohol, fats, sauces, drinks, sweeteners, and dairy products you can consume on the Low-Carb Diet.
Low-Carb Vegetables
Low-carb vegetables are excellent choices for those following the Low-Carb Diet. Here's a list of low-carb vegetables:
- Leafy Greens: Spinach, Kale, Swiss chard, Arugula, Romaine lettuce
- Cruciferous Vegetables: Broccoli, Cauliflower, Brussels sprouts, Cabbage, Kale
- Bell Peppers: Green peppers, Red peppers, Yellow peppers
- Zucchini and Squash: Zucchini, Yellow squash, Spaghetti squash
- Asparagus
- Avocado
- Cucumber
- Tomatoes (in moderation, as they contain some carbs)
- Green Beans
- Mushrooms
Low-Carb Fruits
While fruits generally contain carbohydrates, some are lower in carbs than others. Remember to consume them in moderation. Here's a list of relatively low-carb fruits:
- Berries: Strawberries, Blueberries, Raspberries, Blackberries
- Melons: Watermelon (in moderation), Cantaloupe, Honeydew
- Avocado
- Peaches (in moderation)
- Plums
- Lemons and Limes
- Kiwi (in moderation)
- Guava (in moderation)
- Rhubarb
Low-Carb Nuts
Nuts are generally nutritious but can vary in their carbohydrate content. Here's a list of low-carb nuts:
- Almonds
- Pecans
- Brazil nuts
- Hazelnuts
- Walnuts
- Macadamia nuts
- Pine nuts
Low-Carb Snacks
- Cheese Cubes or Slices
- Hard-Boiled Eggs
- Nuts (in moderation)
- Vegetable Sticks (e.g., cucumber, celery) with Hummus or Guacamole
- Greek Yogurt (unsweetened)
- Beef Jerky (watch for added sugars)
- Cherry Tomatoes
- Olives
- Pork Rinds
- Seeds (e.g., sunflower seeds, pumpkin seeds)
- Avocado Slices
- Berries (in moderation)
- Smoked Salmon or Sardines
- Cheese Crisps
- Pickles
These snacks can provide a satisfying and nutritious option for those following the Low-Carb lifestyle. Remember to check nutritional facts on the labels for hidden sugars and portion sizes to manage your carbohydrate intake effectively.
Learn More: The 25 Best Low-Carb Candy Brands to Buy on the Keto Diet
Low-Carb Alcohol
Alcoholic beverages can vary in their carbohydrate content. Here's a list of relatively low-carb alcoholic options:
- Dry Wine: Red, white, or sparkling wines tend to have lower carbohydrate content than sweeter varieties. Dry wines such as Cabernet Sauvignon, Pinot Noir, Chardonnay, and Champagne are generally good choices.
- Light Beer: Light beers typically have fewer carbohydrates than regular beers. Examples include light versions of popular beer brands.
- Distilled Spirits (Spirits/Hard Liquor): Most distilled spirits, such as vodka, gin, rum, tequila, and whiskey, have zero carbs. However, mixers can contribute to the overall carbohydrate content, so choose low-carb mixers like soda water or diet tonic water.
Learn More: Low-Carb Wine: The 10 Best Red and White Wines
Low-Carb Fats and Sauces
- Low-Carb Fats: Olive oil, Avocado oil, Coconut oil, Butter (preferably from grass-fed cows), Ghee (clarified butter), MCT oil (medium-chain triglycerides), Lard, Duck fat
- Low-Carb Sauces: Mayonnaise (check for added sugars), Mustard, Pesto sauce (watch for added carbs), Soy sauce or tamari (in moderation), Hot sauce (without added sugars), Ranch dressing (choose low-carb varieties), Caesar dressing (watch for added carbs), Sugar-free ketchup or tomato sauce
Low-Carb Drinks
- Water: The best zero-carb drink
- Unsweetened Herbal Tea
- Black Coffee: Plain black coffee without added sugars or syrups
- Green Tea
- Sparkling Water: Plain or flavored, without added sugars
- Unsweetened Almond Milk or Coconut Milk
- Bulletproof Coffee: Coffee blended with butter and MCT oil
- Diet Soda: Some diet sodas are low in carbs, but be mindful of artificial sweeteners.
- Lemon or Lime Water
- Bone Broth
Learn More: 20 Best Zero-Calorie Drinks: Are They Healthy for Weight Loss?
Low-Carb Sweeteners
Here's a list of low-carb sweeteners that are commonly used as sugar substitutes:
- Stevia: A natural sweetener derived from the leaves of the Stevia Rebaudiana plant
- Erythritol: A sugar alcohol that occurs naturally in some fruits and fermented foods
- Monk Fruit (Luo Han Guo): Extracted from the monk fruit, it's a natural sweetener with zero calories.
- Xylitol: Another sugar alcohol found in small amounts in various fruits and vegetables
- Allulose: A rare sugar found naturally in certain fruits, it tastes like table sugar.
- Sucralose (Splenda): A synthetic sweetener that is much sweeter than sugar and has zero calories.
- Aspartame
- Saccharin
Low-Carb Dairy Products
- Hard Cheeses: Cheddar, Swiss, Parmesan, Gouda, Feta
- Soft Cheeses: Cream cheese, Brie, Camembert
- Full-fat Greek Yogurt (unsweetened)
- Heavy Cream
- Grass-Fed Butter
- Sour Cream
- Cottage Cheese
- Mascarpone Cheese
Foods to Avoid on a Low-Carb Diet
On the Low-Carb Diet, you should avoid high-carbohydrate foods like:
- Sugary Foods: Candy, pastries, cookies, cakes, and other sweets
- Grains and Starchy Foods: Bread, pasta, rice, potatoes, breakfast cereals
- High-Sugar Fruits: While some fruits are lower in carbs, high-sugar fruits like bananas, grapes, and mangoes should be avoided or consumed in moderation.
- Legumes: Beans, lentils, and chickpeas
- Processed Foods: Many processed foods contain hidden sugars and unhealthy fats. Avoid items like sugary cereals, energy bars, and pre-packaged snacks.
- Sauces and Condiments with Added Sugars: Check labels for added sugars in sauces like ketchup, barbecue sauce, and salad dressings.
- Sweetened Beverages: Regular sodas, fruit juices, and sweetened drinks
- Alcohol with Added Sugars: Some alcoholic beverages, especially cocktails and sweetened mixers
To help you get started, I have provided a sample 3-day Low-Carb Diet meal plan. You can always change the foods based on your health status, goals, and body needs.
Low-Carb Diet Sample 3-Day Meal Plan
Here's a sample 3-day meal Low-Carb Diet meal plan:
Day 1
- Breakfast: Scrambled eggs with spinach cooked in olive oil
- Lunch: Grilled chicken breast with a side of broccoli and cauliflower
- Snack: Handful of mixed nuts (almonds, walnuts, and pecans)
- Dinner: Baked salmon with asparagus and a side salad with olive oil dressing
Day 2
- Breakfast: Greek yogurt with a few raspberries and a sprinkle of chia seeds
- Lunch: Turkey lettuce wraps with mayo, mustard, and avocado
- Snack: Celery sticks with cream cheese
- Dinner: Zucchini noodles (zoodles) with pesto sauce and grilled shrimp
Day 3
- Breakfast: Omelette with mushrooms, bell peppers, and cheese
- Lunch: Cobb salad with grilled chicken, bacon, avocado, and blue cheese dressing
- Snack: Sliced cucumber with guacamole
- Dinner: Beef stir-fry with broccoli, bell peppers, and snow peas in olive oil
By avoiding high-carb foods and decreasing carbohydrate intake, as you progress into the next levels of the Primal Diet, your body goes through ketosis and experiences more significant positive results.
The main difference between the three levels of the Primal Diet (Low-Carb, Keto, and Carnivore) is the macronutrient ratios, especially the number of carbohydrates you consume.
Low-Carb Diet vs. Keto Diet
The Low-Carb Diet and Keto Diet are the first and second levels of the Primal Diet, emphasize carbohydrate reduction, but here are their key differences:
- Carbohydrate Intake: The Low-Carb Diet allows a higher carbohydrate intake (50-100g/day), while the Keto Diet limits carbohydrates to around 20g/day to achieve ketosis.
- Fat Focus: Keto focuses on high fat intake (around 70-80% of daily calories) to maintain ketosis, whereas the Low-Carb Diet is more flexible with macronutrient ratios.
- Goal: The primary goal of the Keto Diet is to enter and maintain ketosis, while the Low-Carb Diet is more about reducing carb intake for health and weight management without necessarily reaching ketosis.
Low-Carb Diet vs. Carnivore Diet
The Carnivore Diet is an extremely low-carbohydrate (almost zero) version of the Low-Carb Diet. Although it may seem a strict style, it highlights the benefits of going low-carb and helps reduce inflammation and insulin resistance, induce and maintain ketosis, provide autophagy, improve immune function, regulate hormones, and balance blood sugar levels.
This leads to a number of health benefits, which help avoid the root causes of various chronic diseases like stroke, cardiovascular issues, autoimmune conditions, and cancer.
Here are the main differences between the Low-Carb and Carnivore stages of the Primal Diet.
- Foods Allowed: The Low-Carb Diet includes a variety of foods, such as meats, healthy fats, low-carb vegetables, and some fruits, while the Carnivore Diet eliminates all plant foods and focuses solely on animal products like meat, fish, and eggs to maximize the benefits.
- Flexibility: The Low-Carb Diet offers more flexibility with food choices, making it more practical for beginners.
- Plant-Based Foods: The Low-Carb Diet includes non-starchy vegetables, nuts, and seeds. But the Carnivore Diet is completely animal-based.
- Simplicity: The Carnivore Diet is simpler regarding food choices but more restrictive for beginners.
Although a Low-Carb Diet is easy to start for beginners who are used to consuming high-carbohydrate foods, certain groups of individuals need more care and must avoid this diet or begin under the supervision of healthcare professionals.
Who Should NOT Do a Low-Carb Diet?
While the Low-Carb Diet is generally safe, some groups should avoid or approach it with caution:
- Pregnant or Breastfeeding Women: Reducing carbohydrates too much during pregnancy or breastfeeding can lead to nutrient deficiencies.
- People with Kidney Disease: High protein intake in some low-carb diets may stress the kidneys.
- Athletes in High-Intensity Sports: Those requiring quick bursts of energy (e.g., sprinters or CrossFit athletes) may find it difficult to perform optimally on the Low-Carb Diet.
- Individuals with Certain Health Conditions: Anyone with a metabolic disorder or chronic illness should consult a healthcare provider before starting the Low-Carb Diet.
If you’re not among these groups, have pre-diabetes or immune conditions, and have already consulted your healthcare provider, you can consider the following points to start the Low-Carb Diet in a healthy and strong way.
How to Start the Low-Carb Diet?
Starting a Low-Carb Diet can be simple and effective if you follow these steps. It’s all about making gradual changes, focusing on whole foods, and adjusting based on how your body responds.
Step 1: Set Your Carbohydrate Target
Set your carbohydrate target to 50-100 g/day.
Step 2: Clean Out Your Pantry
Get rid of high-carbohydrate foods to avoid temptation. Remove bread, pasta, rice, and cereals; sugary snacks like cookies, candy, and soda; and starchy vegetables like potatoes and corn.
Step 3: Focus on Whole Foods
Consume whole, nutrient-dense foods low in carbohydrates but high in healthy fats and proteins. Prioritize meats (beef, chicken, pork, lamb), fish and seafood (salmon, tuna, shrimp), eggs, healthy fats (avocados, olive oil, butter, and coconut oil), and low-carb vegetables (spinach, broccoli, zucchini, cauliflower).
Step 4: Plan Your Meals
To stay on track, prepare a low-carb meal plan ahead of time. Use simple recipes with ingredients you enjoy.
Step 5: Track Your Carbs
Track your daily carbohydrates to stay within your target range, especially if you’re a beginner. You can use apps like GoCarnivore to easily log the foods you eat and monitor your progress. Remember to focus on net carbs, which are total carbs minus fiber, especially for high-fiber vegetables.
Step 6: Stay Hydrated and Get Electrolytes
When you reduce carbohydrates, your body loses more water and essential minerals like sodium, potassium, and magnesium. To avoid symptoms like the low-carb flu, drink plenty of water, add extra salt to your meals, and take an electrolyte supplement if necessary.
Step 7: Adjust Gradually
Start by cutting out sugary foods and refined grains, then reduce starchy vegetables and high-carb fruits. This gradual adjustment will help you avoid drastic energy dips or cravings in the early stages.
Step 8: Listen to Your Body
As you transition to the Low-Carb Diet, pay attention to how your body reacts. Common experiences include:
- Initial Fatigue or Headaches: This is normal as your body switches from burning carbohydrates to burning fat. Make sure you’re staying hydrated and getting enough electrolytes.
- Increased Energy and Mental Clarity: Many people report more consistent energy and better focus after the adjustment phase.
- Less Hunger: Thanks to the protein and fat content of your meals, you may notice reduced cravings and feeling fuller for longer.
Step 9: Find Support and Stay Consistent
Staying consistent is key to long-term success. You can:
- Join The Primal Lab for tips and motivation.
- Subscribe to The Primal Podcast to listen to discussions with doctors and health experts for hacks and problem-solving.
- Learn Low-Carb Recipes with affordable and delicious ingredients.
- Read The Primal Blog to expand your knowledge of low-carb lifestyle.
- Watch The Primal Videos to access the latest discoveries on the low-carb lifestyle.
- Be patient with the process. Results often take a few weeks to show as your body adapts to fat burning.
Summary
The Low-Carb Diet is the first stage of entering the Primal Diet, which aims to improve your health by decreasing carbohydrate consumption and increasing the intake of fat and protein.
While it’s generally safe to reduce carbohydrates to around 50 grams per day, it’s wise to consult a healthcare professional to ensure going low-carb is in line with your health status and goals.
