Like others said it's technically possible, but why would you want to?

It very much depends on starting weight. Is it possible? Theoretically, yes. Is it safe? No, unlikely for most people.

20lbs or 9kg is a month is extreme weight loss. To lose 1kg of fat, you need a deficit of 7700kcals. For 9 kg that's 69,300 kcals deficit needed over the month. Lets say thats over 28 days / 4 weeks: that'd be an average deficit of 2,475 kcals every day.

An average 30 year old man, who weighs say 80kg and average height.

• Basal Metabolic Rate (BMR) - 1750 kcal a day
• Total Daily Energy Expenditure (BMR x activity factor, lets say 1.2 assuming they are sedentary) - 2,100 kcal a day.

So they need 2100kcal a day just to stay as they are. If they did nothing else, the maximum possible deficit they could have is to eat nothing - but they'd only achieve 2100kcal deficit a day, and they'd not last very long.

For that person to lose 9kg in a month, they would realistically need to massively increase their exercise. Even if they increased their daily energy expenditure to 3,323 kcal a day (1.9 x BMR for a very active person), they'd then need to calorie restrict their diet to only 848 kcal a day to achieve the deficit. Even then a 848kcal intake is dangerously low intake and would require very careful management. And somehow that person would also need to have enough intake to feel able to do all that extra exercise.

It would put the body under extreme stress and be very difficult to maintain.

Now if the person was very severely obese - lets say 200kg - the BMR would be 2949kcal (it takes energy just to maintain the fat), and the TDEE would be about 3540kcal if sedentary (even doing nothing, they use more energy). In that situation, if they suddenly became very active, they could boost their TDEE to say 4000-4500 kcal, and would be able to eat 1690-2190kcal a day, and still have a 2475kcal a day deficit. They could lose the 9kg weight in a month. However it is not very realistic for a severely obese person to go from sedentary to extreme activity in such a short period, and maintain it, and while calorie restricting too.

So it could be done by an obese person, but it's not realistic then and certainly not for anyone who is only overweight.

A big mistake people make when they try to lose weight is to try and fix the problem as fast as possible. But fast dieting leads to over exertion, over strenuous food restriction, failure and then despair. Even 1kg a week lose is a very high rate and difficult to sustain. Instead of trying to lose as much as possible in a month, it's better to aim for a sustainable amount every week for a long time - such as 0.5kg. 6 months of sustained slow lose is generally much more successful and achievable than crash/fast/extreme diets that just fail over and over for 6 months. And generally when people do slow diets, they change habits and have a better chance of maintaining it.

If someone is actually considering a diet then the real key is: don't make it a speed race, make it a marathon. Slightly reduce intake, slightly increase activity every day, and aim for a slow but steady loss. A 550kcal deficit every day is much much easier than trying to rush with 1100kcal deficit, and allows a sustainable lifestyle. For example the 80kg 30 year old person could do moderate exercise (e.g. 10,000 steps a day just walking), they could realistically consume 1900-2000kcal a day, maintain a 550kcal deficit each day and lose 0.5kg every week. In a month they'd lose 2kg, and in 4.5 months they'd lose 9kg.

The normal pace is 1 kg/week (~2lb), faster diet will lead to your body malforming, but it's definitely possible.

Also exercise is not as important as proper diet. It's better to do no exercise and eat little than burn many calories and eat even more.

I think it depends on what % of your body mass that 20lb is. I weigh about 150, if my target was 130 I would take a year to get there. Someone 350lb, maybe yeah a month. The first few lb always faster than the last few, so if all you have to lose is a few pounds it can be slower.

Don't listen to me, I believe all sorts of nonsense.

Weight is not the metric to be measuring by, it fluctuates too much day by day to provide meaningful data and encourages poor behaviors and thought patterns around healthy sizes and shapes.

Most diets work by the grace of being intentional with your food intake via calories/nutrition/macros. Number one thing to do is cut out processed foods. Once your system readjusts to real food it gets really good at self-regulating intake, processed foods are engineered to lie to us to make us eat more. Cravings are our body asking for a nutrient from whatever source it's most familiar with, so get familiar with the good for you foods.

Another aspect of fat cells is they can be full or empty, our body also stores toxins in full fat cells when it can't process them out fast enough and each fat cell can be used about 5-6 times. So to get rid of fat you need to detox firat and to get rid of it permanently you need to use up the cells. Basic idea is get on the losing a kg per week then do one week a month gaining a kg instead of losing one until you hit your goals.

Losing weight too fast can also result in excess saggy skin, losing it slower helps with skin elasticity.

Yes, and more. I dropped 40 pounds in about a month. Although it was due to extreme stress, so I don't recommend that. But, it is physically possible, so there are other routes you can try.

You've probably heard it before, but the key to quick fat loss is dropping carbs, including beer. Sorry.

Track your carbs using a macro tracking app, because you don't know how many carbs you are eating, you just don't, and you'll be surprised. Once you learn which foods are full of carbs, you can stop using the app, it's just a learning tool, not something you need to keep doing.

Get it below 100g a day, and watch the fat burn away, and you'll start feeling so much better, after the first couple of weeks. It can be a hard adjustment for some people, but it's worth it.

Exercise is only about 20% of it, diet is 80%, which makes sense. It's much easier to not consume the food in the first place, than to burn it off after it's already fat.

However, to be healthy, not just lose fat, you need to do both diet and exercise. That's why it's always presented that way--"diet AND exercise", not "diet OR exercise".

It's best to make the commitment to a permanent lifestyle change, rather than just aiming for a goal weight and then going back to drinking beer every day. You'll QUICKLY gain the fat back, faster than you lost it, and that is disheartening.

If you just give up, you could end up with type 2 diabetes in 15 or 20 years, and that makes being old much worse. So, it's worth the effort.

You can drop 20 pounds in a month, but you probably shouldn't unless your overall size and weight make 20 pounds not as significant as it would be to the average human.

There's a lot of serious illnesses/medical conditions that will make you loose a lot of weight, very fast. I think i.e some cancers are one of those.

They usually also kill you pretty quickly, but you didn't ask for healthy.

This is more of a reminder - if you inexplicably loose a lot of weight, it's not something to celebrate, but get checked up ASAP.

No idea, but any diet that involves weight loss will also need you to quit beer entirely.

A pound of fat equates to, very roughly, 3500 calories. So you would need a deficit of over 2300 calories per day to lose that much weight in a month. Try to keep your calorie level above 1200/day at a minimum. So if you're drinking so much beer and eating so much food you're currently consuming 3500 calories/day or more, then yes, it would be possible. But that's not exactly a healthy amount of weight loss. Even halving the rate would still be pretty aggressive. I get wanting to see tangible progress, but I would strongly encourage you to do this over two months instead of over a month.

I am assuming your are in your 20s. When I was in my 20s I could loose five pounds in a week just be maintaining my excercise routine and diet.

If you can go five miles a day, than eat 1200 calories a day or less and stop drinking. You will shed 20 pounds in no time.

FYI: You didn’t say you wanted the plan to be healthy.

Everyone here talking calories and forgetting water weight. Boxers etc. will drop carbs entirely to make a weight cut-off. Two aspects to consider here, glycogen and inflammation, both of which store water. If you are not fat adapted and stop carbs your glycogen will deplete (~500g glycogen + 4x that in water, 2.5kg = 5+lbs), also called hitting the wall in endurance sports.

If you have systemic inflammation your fat cells will carry a bunch of extra water (you know when your ankle swells up after twisting, that's water from inflammation), so removing inflammatory stimuli, foods, environment can cause that to get peed out. Depending how many fat cells, the amount will vary, but could easily be 5kg if obese.

This is how people lose dramatic amounts of weight in the first few weeks of diet. Actually removing fat is a lot harder, but it starts in the kitchen.

20 lbs of fat is 70,000 Calories. That means that you need to be at a net deficit of about 2300 Calories daily to lose 20lbs in a month. That's a huge deficit which would require eating little and working very hard to hit anything near that.

The first month, yes. In general that is not healthy to aim for. In general extreme programs are not healthy and not sustainable

At one point i used weight watchers to successfully lose a lot of weight - I lost 109 pounds over a couple years as planning for being better able to care for kids. This is a regular program, very much not extreme. However a key part of their program was weekly weigh-ins.

Their recommended intake varies by age, size and gender: I think I started at 2100 calories/day and was down to 1800 as I was reaching my goal. Meanwhile my ex’s target was 1200 calories/day

The programs goal was to lose about 2 pounds/week and focus on sustainable life changes - keeps you healthy with regular weight loss. However everyone had much bigger losses the first couple of weeks. I’m sure I lost more than 20 pounds my first month on the program, but it was water weight, not repeatable. Certainly not a healthy goal

Of course you can, the question is should you?

If you don't eat for a month you'd drop 10 kilos. But then you'd grow them back with interest.

Better to lose maximum 1 kilo (2 lbs) per month if you really want to lose it.

And yeah, beer isn't the way forward for sure, except if you aim for a big belly and skinny legs...

Ditching all sugars is a good start IMO.

Good luck!

Not a doctor, but used to cut a lot of weight and can regurgitate some of the stuff I was told that's definitely too specific to be universally true but might give good hints.

"The body can't burn fat off past a certain rate, ~3pbs / week. Any weight loss beyond that is probably mostly dehydration."

"Alcohol metabolizes to sugar up to the point that you can't metabolize it anymore, and it starts getting you drunk. Any time you catch a buzz, you've also basically eaten a bowl of candy."

My two bits: firstly try to eat as healthy as you can, meaning definitely cut all sugar, then try to cut carbs generally, then fats and salts. Weight yourself every morning before you eat. Take it slow, aiming for a couple of pounds a week (just under your 20lbs/month goal). If you're not on pace, ramp up exercise a lot (especially cardio) and trim your intake a little. (More exercise better than less food.). Stay well hydrated the whole way. It'll help your body process all the challenges.

Hate to break it to you brother, but you definitely want to cut the beer while you're trying to get to your target weight. Maybe you can figure it out without doing that, but that's hard mode for sure, and I don't think you'd be asking for tips if you were really ready for hard mode.

Amputation

Stop drinking beer.

If you're serious and your doctor thinks it's fine (and you have some extra money) you can go on a glp-1 but even then a doctor wouldn't recommend more than 2 lbs / week. I know people that have lost 10-15 lbs in the first few weeks so I'm sure it's not out of the question. There are healthier ways to lose weight though.

Sure, I lost 28 lbs in one month when I was first developing type 1 diabetes.

Other than that, you might want to do calorie calculations. Exercise is great, but it takes a surprising amount of work to counter a given amount of calories. I've been tracking my walking with an app that estimates calories, and 4-5 miles is just getting started. I've been walking 6-10 miles a day. The app and online sources say 5 miles burns ~500 calories, which is 2-3 beers depending on the type. So exercise like that might be able to stave off weight gain, but it's unlikely to result in weight reduction. You'd likely want to analyze your diet and cut out any calories over what is medically necessary. Burning more than what you take in results in weight loss. Just be sure you're covering the basic macros, especially protein, and getting enough electrolytes and vitamins.

It's possible. Just depends how fat you are. If you're 500lbs, and do a crash diet, sure. Maybe even more.

If you're 140lbs......ehhhh......maybe not.

Drink lots of water, to help with skin elasticity. Losing more than 3 lbs a week normally results in extra saggy skin.

Generally it’s best not to focus on losing weight but on adjusting calorie intake. Because muscle weighs more than fat, water weighs more than either, and the goal is generally to feel fit, not light.

When wrestling I used to do the “drop a kilo class” thing by bulking up in a way that could rapidly store water, then running to temporarily shed that water before weigh in, then immediately rehydrate up to the next weight class. That was usually around 10 lbs of weight, but I was dropping it and regaining within a 6 hour period.

Losing weight for health reasons isn’t going to be the same for everyone. Personally I find the best way for me to lose weight is to increase my metabolism, which I find I can do through endurance running in threshold temperatures. But for other people that just makes them tired and hungry without their metabolism adjusting. And without the metabolic change, you don’t get the added benefit of literally burning off stored energy.

Also, depleting fat cells isn’t the same as removing fat cells. Those cells are still there, and it’s going to take months for cellular change to happen in your body. So 20 lbs of weight loss in a month will mostly be loss of water, muscle, and energy stored in the fat cells. And as soon as you stop starving yourself, it’ll all come back. And that can happen in a matter of days.

I lost about 5-10 pounds a week for a while when I first started losing weight. But I was also extremely overweight.

Actors are liteypaid for their body so they can dedicate their entire time (and crazy amounts of money) into a diet and exercise routine.

Yeah sure, liposuction exists and you should be able to recover in a month as well. GLPs exist as well, but you wouldn't lose that much. With laxatives you could lose enough body water as well, not bodyfat, but still weight.

As for avarage person, under normal circumstances and doing it sustainably. Basically no.

The 5 miles of walking is roughly around a full sized Snicker bar. "You can never outrun a bad diet"

Losing roughly 1% of bodyweight per week is the upper limit of sustainable fat loss.

Though a month is a good timeframe to make a start. Don't think of it as dieting as it will give you an expression that your doing it temporarily, see it more as a lifestyle change. First start tracking your weight. 2-3 times a week, under same conditions aka first thing in the morning after taking a leak, use avarage numbers. At the same time reduce the amount of beer your drinking, just an easy way to reduce caloric intake without a hit to nutrient intake. After a month see how the bodyweight has shifted, at first probably quitting beer is enough to start it to shift downwards, then just keep it up and have patience. Weight loss is measured on a scale of weeks to months. Personally i lost nearly 15+kg over the course of half a year by just quitting beer and not even doing anything else.

I lost 15 pounds in March. I was eating an average of 1,100 calories per day.

I mean it’s close to doable but you’d be pushing what’s healthy in terms of weight loss. The problem with rapid weight loss is mainly yo-yo dieting. You usually use a fad/crash diet that isn’t sustainable long term and then gain it back. Lifting + some cardio is the best bang for buck in terms of calories burnt for most in terms of time/effort.

The boozing is a problem for a couple reasons (beyond the obvious reasons, but I’ll spare you the sermon there). One beer is ~112cal. Maintenance for me was -2200cal back in the day. Drinking ten beers, which back when I was boozing was enough to get a buzz going. That’s 1120cal, eating at a loss for me was 1600-1700cal if I recall. So one night’s buzz undoes 2 days dieting, at least.

If you then eat to account for it, you run the risk of getting most your calories from booze, which can be incredibly harmful for you long term, I.e. deadly I’m pretty sure.

If you want to do it naturally, combining prolonged water fasting and endurance exercise is the way.

I once lost 18 lb in 10 days with it. I am already quite lean so I stopped.

You have to build up to it. Both in terms of walking or slow running long distances and being fat adapted. I started with intermittent fasting, omad etc.

Water fasting would be my best bet.

You can’t be in more caloric deficit and ketosis than by simply not eating.