Lose Up to 10 Lbs Fast: Best Diets That Actually Work

Quick weight loss diets are structured eating plans designed to help individuals lose weight over a short period—typically within 1 to 4 weeks. These diets usually aim to create a calorie deficit through restricted eating windows, reduced carbohydrates, or meal replacements.

Some of the most recognized diets for fast weight loss include:

• The Keto Diet (low-carb, high-fat)

• Intermittent Fasting (timed eating, e.g., 16:8 or 5:2)

• SlimFast Plan (meal replacements)

• Military Diet (low-calorie, 3-day plan)

• Low-Carb Mediterranean Diet (vegetable-heavy with reduced grains)

While these diets differ in approach, what unites them is their ability to reduce water weight, glycogen stores, and in some cases, fat mass relatively quickly—especially in the first 1–2 weeks.

How Quick Weight Loss Diets Work: Key Mechanisms Explained

Quick weight loss is not magic—it’s biology. Here’s how these diets often trigger fast results:

🔹 1. Lower Carbohydrates → Reduced Water Retention

Carbohydrates are stored as glycogen in the body, which holds 3–4 grams of water per gram. Cutting carbs rapidly depletes glycogen and water, leading to noticeable early weight loss.

🔹 2. Ketosis (in ketogenic diets)

In very low-carb diets, your body enters ketosis, burning fat for fuel instead of glucose. This metabolic switch accelerates fat loss and suppresses appetite through ketone production.

🔹 3. Intermittent Fasting → Insulin Control

Restricting eating times lowers insulin levels, enhancing lipolysis (fat breakdown) and reducing overall calorie intake—without needing to track every bite.

🔹 4. Meal Replacements Reduce Decision Fatigue

Plans like SlimFast simplify meals, replacing breakfast and lunch with controlled shakes or bars. This minimizes mindless eating and calorie overshoot.

🔹 5. Protein and Fiber Satiety Boosters

High-protein and fiber-rich diets prolong satiety, increase the thermic effect of food, and stabilize blood sugar—all contributing to reduced snacking and fewer cravings.

Scientific Evidence Behind Fast Weight Loss Diets

✅ Intermittent Fasting

A 2020 review in Frontiers in Nutrition found that intermittent fasting led to weight loss of 0.8% to 13% of body weight over 2–12 weeks, especially in overweight adults.

✅ Keto Diet

In a Nutrition & Metabolism clinical study, participants on a ketogenic diet lost 2.2 times more weight than those on a low-fat diet within 12 weeks, even when eating until fullness.

✅ SlimFast Meal Replacement Plan

A 2018 Journal of Nutrition study showed that SlimFast users lost 11 pounds more over 6 months compared to a conventional calorie-restricted diet.

✅ Military Diet

While lacking long-term trials, the Military Diet claims up to 10 pounds in one week, largely from water loss and reduced caloric intake (~1,000–1,200 kcal/day).

💬 Dr. Lisa Young, RD and adjunct professor at NYU, notes:

“Diets that promote rapid weight loss can be effective jumpstarts—but sustaining the loss requires long-term behavior change, especially when it comes to sugar, sleep, and stress.”

Quick Weight Loss Diets by User Type

Practical Applications: How to Follow These Diets Safely

🍽️ 1. SlimFast Meal Plan (Example)

• Breakfast: SlimFast Protein Shake

• Snack: Apple with peanut butter

• Lunch: SlimFast Meal Bar

• Snack: Baby carrots and hummus

• Dinner: Grilled salmon, quinoa, steamed broccoli

💡 Add real meals for dinner to stay grounded in whole-food nutrition.

🕒 2. 16:8 Intermittent Fasting

• Fasting Window: 8 PM – 12 PM (next day)

• Eating Window: 12 PM – 8 PM

• Meal Tips: Break fast with protein-rich, fiber-heavy meals to avoid rebound cravings.

🥦 3. Military Diet (3-Day Cycle)

• Day 1 Example:

  • Breakfast: 1 slice toast, 1 egg, half grapefruit

  • Lunch: 1 slice bread, ½ cup tuna

  • Dinner: 3 oz meat, 1 cup green beans, small apple

• Repeat 3 days on / 4 days normal eating

⚠️ Due to low calories, avoid heavy exercise during Military Diet weeks.

Risks & Precautions

Quick-fix diets can trigger side effects, especially when calorie intake drops below 1,200 kcal/day:

• Dizziness or fatigue

• Hair thinning

• Electrolyte imbalances

• Gallstone formation (common with rapid weight loss)

• Loss of muscle mass

❗Avoid These Diets If You:

• Are pregnant or breastfeeding

• Have a history of eating disorders

• Are on blood sugar or blood pressure medications (consult your doctor)

• Have chronic kidney issues

🛡️ Always consult a healthcare provider or registered dietitian before starting a restrictive diet. Supplements and shakes are often unregulated and may contain hidden sugars or allergens.

Can These Diets Support Long-Term Success?

Short-term diets work best when they act as a launchpad into deeper, sustainable health habits.

Instead of yo-yo dieting:

• Transition into a Mediterranean-style pattern

• Pair diet with resistance training and walking

• Prioritize consistent sleep (7–8 hrs/night)

• Manage chronic stress, which disrupts cortisol and fat storage

🧘‍♀️ Small, consistent habits—not severe restrictions—are what protect your results.

FAQs About Best Diets for Quick Weight Loss

❓1. How much weight can I lose in two weeks with these diets?

Most people lose 4–10 pounds, but the first 3–5 lbs are typically water weight. Actual fat loss averages 1–2 lbs per week.

❓2. Which is faster: keto or intermittent fasting?

Keto may show faster initial weight drop due to water loss and ketosis, but intermittent fasting is easier to maintain for some and may have better long-term adherence.

❓3. Can I work out during these diets?

Yes—but avoid high-intensity workouts if you’re eating <1,200 calories. Moderate walking or resistance training is safe and helpful.

❓4. Are diet shakes like SlimFast safe?

Generally yes if used short-term and as directed. However, check for added sugars and low-quality ingredients.

❓5. What’s the safest plan for women over 50?

Low-carb Mediterranean diets are ideal—rich in omega-3s, fiber, and antioxidants, with minimal processed foods.

✅ Final Takeaway

The best diets for quick weight loss can be useful tools—especially for a motivational jumpstart—but they’re not long-term solutions by themselves.

Choose an approach that fits your lifestyle, start slow, and always put nutrition, sustainability, and self-compassion at the center of your weight loss journey.

“Fast results are possible—but lasting results are powerful.”

— Certified Nutritionist Ashley Harper, RD