What happens when you cut out sugar and starch?

November 6, 2025 •

4 min read

Studies have shown that excessive intake of added sugar contributes to weight gain, increased risk of type 2 diabetes, and heart disease. This raises a key question for many people considering a dietary change: what happens when you cut out sugar and starch?. The body undergoes a series of adjustments, from initial withdrawal to long-term health improvements.

Quick Summary

Eliminating sugar and starch triggers an initial adjustment period with withdrawal symptoms like fatigue and headaches. However, it quickly leads to stabilized energy, reduced cravings, and significant long-term health benefits, including weight loss and improved metabolic health.

Key Points

Initial Withdrawal Symptoms: Prepare for temporary headaches, fatigue, irritability, and cravings as your body adjusts to burning fat instead of sugar.
Long-term Health Benefits: Expect stable energy, reduced cravings, improved mental clarity, and significant improvements in blood sugar control and heart health.
Water and Fat Loss: Initial rapid weight loss is often water weight, followed by more gradual fat loss as your body enters a state of ketosis.
Enhanced Appetite Control: A diet focused on protein, fiber, and healthy fats increases satiety, naturally leading to a reduced appetite and overall lower calorie intake.
Sustainable Strategies: Focus on adding nutrient-dense whole foods and making gradual changes rather than a drastic 'cold turkey' approach to ensure long-term success.
Improved Metabolic Markers: The dietary change can lead to healthier blood lipid profiles, including lower triglycerides and higher HDL (good) cholesterol.

The Initial Shock: Navigating the First Week

When you first decide to cut out sugar and starch, the body undergoes a significant adjustment period often referred to as the 'keto flu'. Your body, accustomed to relying on glucose (blood sugar) from carbohydrates for quick energy, must now find an alternative fuel source. This involves transitioning to burning stored fat for energy, a metabolic state known as ketosis. During this switch, it is common to experience a range of unpleasant, but temporary, withdrawal symptoms.

Common Withdrawal Symptoms

Headaches and Brain Fog: A sudden drop in blood sugar levels can trigger headaches as the brain adjusts to a new fuel source. You might also experience brain fog or trouble concentrating.
Fatigue and Irritability: Without the constant energy spikes from sugar, you may feel sluggish and moody. This fatigue is a sign that your body is re-calibrating its energy metabolism.
Intense Cravings: Sugar stimulates the brain's reward center via dopamine, creating a cycle of cravings. Initially, these cravings may intensify, but they typically subside as your brain's dopamine receptors reset.
Digestive Discomfort: A diet high in fiber from whole foods replaces low-fiber refined carbs. This change can initially cause bloating or constipation, but it typically improves digestive health long-term.
Water Weight Loss: A quick and noticeable change is the shedding of water weight. The body depletes its glycogen stores, which are bound to water, leading to rapid initial weight loss.

The Shift to Lasting Benefits

After the initial adaptation phase, which can last from a few days to a couple of weeks, the body's new metabolic state offers a host of significant health benefits that often make the initial discomfort worthwhile.

Stabilized Energy Levels

Instead of experiencing dramatic blood sugar spikes and crashes, your energy levels will become more stable and sustained throughout the day. This happens because the body is now using fat for a steady, long-lasting energy supply, eliminating the midday slump associated with high-sugar diets.

Enhanced Mental Clarity

Many people report improved focus, better cognitive function, and reduced brain fog after the initial withdrawal period. Stable blood sugar levels help support better brain health and mood regulation.

Appetite and Weight Management

Cutting out processed sugars and starches, which offer little nutritional value, naturally reduces your overall caloric intake. Replacing these with nutrient-dense foods rich in protein, fiber, and healthy fats helps you feel fuller for longer, which can significantly aid in weight loss. A low-carb diet has also been shown to improve appetite control by affecting hunger-regulating hormones like leptin.

Improved Metabolic Health

One of the most profound benefits is the improvement in various metabolic markers. This includes better blood sugar control, increased insulin sensitivity, and positive changes in blood lipid profiles. Low-carb diets can decrease triglyceride levels and increase 'good' HDL cholesterol. This can lower the risk of developing type 2 diabetes and heart disease.

Comparison: High Carb vs. Low Sugar/Starch Diet


Feature	High Refined Sugar/Starch Diet	Low Sugar/Starch Diet (Whole Foods)
Primary Energy Source	Glucose from carbohydrates	Ketones from stored fat
Blood Sugar Levels	Frequent spikes and crashes	Stable and controlled
Appetite and Cravings	High cravings, less satiety	Reduced cravings, increased satiety
Weight Management	Linked to weight gain and obesity	Promotes weight loss, especially fat loss
Inflammation	Can increase chronic, low-grade inflammation	Helps decrease inflammation
Gut Health	Can harm gut health due to lack of fiber	Supports a healthier gut microbiome with increased fiber
Energy Levels	Peaks and crashes; can lead to fatigue	Sustained and steady throughout the day

Making the Change Sustainable

Transitioning to a lower-sugar and lower-starch diet is most effective when done gradually. A 'cold turkey' approach can be overwhelming and increase the risk of a relapse. Focus on adding nutrient-dense whole foods to your diet rather than just subtracting the unhealthy ones.

Practical Strategies

Prioritize Protein and Healthy Fats: Incorporate lean proteins (meat, fish, eggs) and healthy fats (avocado, nuts, seeds) to increase satiety and provide a steady energy source.
Fill up on Fiber: Choose non-starchy vegetables like leafy greens, broccoli, and peppers. The fiber will keep you full and improve digestive health.
Stay Hydrated: Drinking plenty of water is essential for flushing toxins and can help manage cravings and fatigue during the adjustment period.
Read Food Labels: Sugars and refined starches are hidden in many processed foods under various names. Become a pro at reading labels to identify and avoid them.
Exercise Regularly: Physical activity helps boost mood and energy, which can counteract the initial withdrawal symptoms.

Conclusion

Making the decision to cut out sugar and starch is a significant step toward improving your overall health. While the initial withdrawal period can be challenging, it is temporary and a normal part of the body's detoxification process. The long-term rewards, including stable energy, reduced cravings, better metabolic function, and potential weight loss, are well worth the effort. By focusing on whole, nutrient-dense foods and making gradual, sustainable changes, you can successfully navigate this dietary shift and set yourself up for a healthier future. For more information, consult authoritative sources like Mayo Clinic's guide on low-carb diets.

How to Avoid Common Pitfalls

Don't Fear All Carbs: The goal is to eliminate refined carbs and added sugars, not all carbohydrates. Fiber-rich, complex carbs from sources like whole grains and legumes still offer valuable nutrients.
Address Emotional Triggers: For many, sugar consumption is linked to stress or boredom. Identify these triggers and find healthier coping mechanisms.
Consult a Professional: For a personalized plan, especially if you have pre-existing health conditions like diabetes, consult with a doctor or a registered dietitian.

Frequently Asked Questions

Within the first few days, you'll likely experience withdrawal symptoms such as headaches, fatigue, and irritability, commonly called the 'keto flu'.

For most people, the most intense withdrawal symptoms pass within the first week or two as the body adapts to its new metabolic state.

Yes, many people experience weight loss. Initially, much of it is water weight, but long-term fat loss is a common benefit as cravings decrease and you consume fewer calories.

Focus on nutrient-dense whole foods like lean proteins, healthy fats, fiber-rich vegetables, and whole fruits. These will provide sustained energy and keep you feeling full.

Yes, whole fruits provide natural sugar along with fiber and nutrients. However, it's best to consume them in moderation and focus on lower-sugar options like berries.

It is not recommended to cut out all carbohydrates entirely, as this could lead to nutrient deficiencies. The focus should be on eliminating added sugars and refined starches while consuming nutrient-rich complex carbs in moderation.

Staying hydrated, increasing your intake of protein and fiber, and finding alternative ways to manage stress and boredom can help curb sugar cravings. They will also naturally decrease over time.