Losing 40 Pounds in 3 Months: What You Need to Know, According to Experts

Tips for losing weight and keeping it off for good

Co-authored by Laura Flinn and Kyle Hall

Last Updated: September 25, 2025 Fact Checked

• Can you lose 40 pounds in 3 months?
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• How fast can you lose 40 pounds?
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• Expert Tips for Losing Weight
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• The Bottom Line
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• Real Stories & Perspectives
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• Video
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• Warnings

|Show more |Show less

How quickly you’re able to lose weight can depend on a lot of individual factors, including your current weight and overall health. Generally speaking, though, most experts say it’s safe to lose 1-2 pounds (0.5-1 kg) per week, which comes out to be around 12-24 pounds over 3 months. But there’s more to it than that, and to help you achieve your goals, we spoke to fitness and weight loss experts and got their best tips and secrets for shedding pounds and keeping them off.

Losing 40 Pounds in 3 Months: Quick Overview

NASM certified personal trainer Laura Flinn says losing 1-2 pounds per week is a healthy weight loss goal. At that pace, you could lose 40 pounds in as few as 5 months, but not 3 (unless you’re working with your doctor to lose weight at a faster pace). Some expert tips for losing weight include:

• Eating 500-1,000 fewer calories per day
• Choosing whole foods (fruits, vegetables, whole grains, and lean protein)
• Avoiding fad diets
• Exercising consistently throughout the week
• Prioritizing a healthy lifestyle overall

Steps

Section 1 of 5:

Can you lose 40 pounds in 3 months?

1. 
   It may be possible, but for the average person, it’s not recommended. Most experts agree that losing 1-2 pounds (0.5-1 kg) of weight per week is a safe, sustainable goal. “When I work with someone on their weight loss goals, I advise them to aim for 1-2 pounds a week for a healthy weight loss, which is around 9-18 pounds in 2 months,” says NASM certified personal trainer Laura Flinn. At this safe, recommended pace, you could lose up to 24 pounds in 3 months, but not 40 pounds.

   • With that said, people who are obese may be able to lose weight faster. “If someone has 50 pounds to lose, they will lose weight faster than someone who has a few pounds to lose,” says Flinn.
   • If you have an obesity-related health condition, your doctor may recommend a very low calorie diet (VLCD), which involves eating fewer than 800 calories per day and can lead to faster weight loss. However, this should only be attempted under the supervision of your doctor since it isn’t always safe or recommended.

   Meet the wikiHow Experts

   Laura Flinn is a National Academy of Sports Medicine (NASM) Certified Personal Trainer, USA Olympic Weightlifting Sports Performance Coach, and Certified Fitness Nutritionist who specializes in weight loss and fitness.

   Kristi Major is an ACE certified Personal Trainer based in the San Francisco Bay Area with over 18 years of personal training experience and more than 90 hours of recertification study in fitness, health, nutrition, and supplementation.

   Pouya Shafipour, MD, MS, is a Family Medicine Specialist, Primary Care Physician, and Weight Loss Specialist based in Santa Monica, California who specializes in dietary, nutritional, behavioral, and exercise counseling.

   Pete Cerqua is a Certified Personal Trainer and Nutritionist and five-time best-selling author with over 20 years of personal training and nutrition coaching experience.

   Jesse Gaynor is a Fitness and Health Trainer and the Owner of Jesse Gaynor Fitness & Wellness, based in the Los Angeles Metropolitan Area. With over 15 years of experience, he specializes in personal training, nutrition, and pain and injury recovery.
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Section 2 of 5:

How fast can you safely lose 40 pounds?

1. 
   Following recommended guidelines, you may be able to lose 40 pounds in as few as 5 months. While it’s not as short as 3 months, aiming to lose 40 pounds in 5 months instead is safer and more sustainable, meaning you’re more likely to keep the weight off in the long run. “When you try [a] new overhaul to lose weight quickly, I've never seen that really truly stick,” says ACE certified personal trainer Kristi Major, cautioning that a slower, steadier weight-loss goal is the better choice. To lose 40 pounds in 5 months, you would need to lose 2 pounds per week, which is within the recommended 1-2 pounds per week pace set by experts.

   • To lose 2 pounds per week, reduce your daily caloric intake by around 1,000 calories.

Section 3 of 5:

Expert Tips for Losing Weight

1. 
   1
   Eat 500-1,000 fewer calories per day. This decrease in your daily caloric intake can help you lose 1-2 pounds per week, which is about 40 pounds over 5-10 months. Here’s an easy way to figure out how many calories per day you should aim for based on your current weight:

   • Multiply your current weight by 15.
     • For example, 200 pounds x 15 = 3,000
     • In this example, that means you need 3,000 calories per day to maintain your current weight.
   • Subtract 500 or 1,000 from that number, depending on how many pounds you’re aiming to lose per week (500 for 1 pound per week; 1,000 for 2 pounds per week).
     • For example, 3,000 - 1,000 = 2,000
     • In this example, that means you should aim to eat 2,000 calories per day to lose 1 pound per week.
   • This calculation assumes you’re getting at least 30 minutes of physical activity per day
2. 
   2
   Eat more whole foods and limit processed ones. Whole foods include fruits, vegetables, nuts, legumes, whole grains, and meat that has been minimally processed. Processed foods, on the other hand, are foods that contain additives and extra ingredients (think packaged snacks and fast food), and they’ve been associated with a higher risk of obesity and overeating. Weight loss specialist Pouya Shafipour, MD, MS, recommends “Significantly reducing refined sugar, simple starches, fast food, fried food, dried fruits, soda, and juices and focus[ing] on a diet high in vegetables and healthy sources of plant or animal-based protein and plant or animal-based fat.”

   • Rather than choosing one particular weight-loss diet, aiming to eat more whole foods and fewer processed ones in general can help you develop healthier eating habits that will keep the weight off once you lose it.
   • Certified personal trainer and nutritionist Pete Cerqua agrees. “Don't go with the 'keto this' and the ‘all fruits diet’ and the Atkins and the South Beach and everything that's been recycled 100 times,” he says. “Make it a lifestyle change and something that's sustainable for 10, 20, 30 years.”
3. 
   3
   Exercise consistently. While reducing calories and eating a healthy diet are the primary ways to lose weight, regular exercise can help you maintain your weight loss. Plus, it’s great for your health in general! Aim to do at least 150 minutes per week of moderate-intensity aerobic exercise (or 75 minutes of vigorous intensity). That’s about 30 minutes per day, 5 days a week. Also include 2 days of strength-training exercise each week.

   • Some examples of moderate aerobic exercise include brisk walking, going for a bike ride, gardening, hiking, and rollerblading.
   • Vigorous aerobic exercise includes running, playing sports, and speed or hill cycling.
   • Strength training can be accomplished through weightlifting, bodyweight exercises, or using resistance bands.
   • Dr. Shafipour recommends starting slow if you’re new to exercising. “At the beginning of [a] weight loss program, I do not recommend intense exercise, which can make people hungry and discourage them from adhering to [their] diet."
4. 
   4
   Focus on your reasons for losing weight to stay motivated. “Why do you want to [lose weight]? That's where you'll find your biggest willpower,” says success strategist Sharon Lee. “It has everything to do with the mental strength of the desire to do it. You have to have a reason to do it.” Whether you’re trying to lose weight for your health, aesthetic reasons, or something else, keep that reasoning at the front of your mind to stay driven. It will make sticking to healthier eating and exercising easier in the long run.
5. 
   5
   Talk to your doctor about weight loss medications. Depending on your weight, health history, and success with traditional weight loss methods, your doctor may prescribe medication to assist with weight loss. Some medications are taken orally, like Orlistat, while others are injected, like semaglutide, tirzepatide, and liraglutide. Talk to your doctor to learn more about whether you’re a good candidate for weight loss medication and what the potential side effects may be.
6. 
   6
   Ask your doctor if you’re a candidate for weight loss surgery. Weight loss surgery, also called bariatric surgery, is usually only recommended for people with serious health conditions caused by their weight, and when traditional weight loss methods haven’t been effective. If you think you’d be a good candidate, talk to your doctor about your options and the potential risks.
7. 
   7
   Focus on living a healthy lifestyle overall. "Focus on getting healthier, and your weight will drop,” says fitness and health trainer Jesse Gaynor. “Drink more water, move your body or walk more, and make the simple changes you already know improve your health." Danny Gordon, a certified personal trainer, agrees. “I always tell people: first focus on your health, because that's number one. Without your health, you don't have anything. So focus on your health and on saying, ‘I want to live healthier, I want to be better about the choices that I'm making.’”
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Section 4 of 5:

The Bottom Line

1. 
   Losing 40 pounds in 5 months is a safer, more sustainable goal. You can achieve this goal by reducing your daily caloric intake by 1,000, prioritizing whole foods over processed foods, and exercising consistently to maintain your weight loss. If you have weight-related health conditions, talk to your doctor about medical interventions, like medication and surgery, that can be used in conjunction with diet and exercise.

Section 5 of 5:

Real Weight Loss Stories & Perspectives

1. Weight loss is a personal journey, but you don’t have to figure things out alone. Many people struggle (and succeed) in losing weight, and their experiences don’t all look the same. Check out these stories and insights from other wikiHow readers (and experts) to discover unique weight loss tips and perspectives:

   • I’ve Tried Everything and Can’t Lose Weight
     • “After I made the switch to drinking water only, I started dropping pounds.”
   • Realistically, How Much Weight Can I Safely Lose in One Month?
     • “Opt for lean rather than fatty proteins. I like a healthy turkey chili—it’s flavorful but still good for you!”
   • How Do I Lose Fat and Gain Muscle?
     • “I incorporated more cardio and weight training into my routine to burn more calories.”
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Warnings

• Talk to your doctor before drastically changing your diet or exercise regimen.
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• Avoid attempting a very low calorie diet (VLCD) unless under the supervision of your doctor.
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