There are advantages and disadvantages of each.
First, let's talk about fast weight loss simply because there's so much misunderstanding around it and so many wrong-headed ideas. After that we'll consider the pros and cons of slow and steady, followed by a discussion of mixing both fast and slow methods.
There are many experts, nutritionists, even government authorities that claim that by losing rapidly, you'll also regain the rapidly (and then some). Or that you're ruining your metabolism. Or you're on a starvation diet.
Studies show none of that is true.
Regarding so-called "starvation mode" and ruining metabolism, the bottom line is that there is no such thing as starvation mode the way everyone talks about it in mainstream media, dieting circles, or almost anywhere else. For a clear-headed explanation of what's really going on, see Metabolic Adjustments.
Now, let's talk about studies regarding rapid weight loss and how it relates to long-term success (vs weight regain).
A study in 2010 at the University of Florida analyzed 262 middle-aged obese women. They were put on fast, moderate, and slow programs. It turned out that women in the fast group were five times (500%) more likely than the slow group to achieve the goal of 10 percent weight loss ... AND they maintained it longer.
In October, 2014, another study was published. It was led by Joseph Proietto, Professor of Medicine at the University of Melbourne and Head of the Weight Control Clinic at Austin Health in Australia. He gathered 200 obese adults and randomly assigned them to one of the following:
1) A 12-week VLCD (450-800 calories per day)
2) A 36-week gradual program that cut calories by roughly 500 a day.
The result? 81% of participants on the "fast" program reached their benchmark of 12% loss of body weight. Only 50% of the "slow" program made it. For another 3 years, researchers continued to follow those who had reached that benchmark. To their surprise, the "fast" group had NOT gained back more weight than the "slow" group. Losing fast had not hurt long-term results at all.
Dr Corby Martin from the Pennington Biomedical Research Center, Baton Rouge, USA says, "The study...indicates that for weight loss, a slow and steady approach does not win the race, and the myth that rapid weight loss is associated with rapid weight regain is no more true than Aesop's fable."
Too many people look at every weight loss idea, strategy or program as if it is something you need to do for a lifetime. That's silly. With any goal (weight loss or otherwise), there are short-term strategies you use to reach long-term goals.
That's the case with rapid weight loss. It's a mistake to compare it to more gradual or long-term lifestyle changes. They're two different things. Most rapid weight loss programs are designed to be done in a relatively short time period followed by a break. You only need to sustain the diet for a short time, then you're done.
On the other hand, if you're following a diet, program or strategy for many months, then of course you need to consider if it is a balanced diet and sustainable.
Even then -- what is considered "sustainable" or balanced may not be what you think. Some obese people have gone entirely without food (fasting) for weeks, months, even a year, living off fat stores, without any significant health problems! It's hard to be critical of low calorie diets or even "extreme" diets when you consider these fasting case studies.
Losing weight quickly can provide a great jumpstart to long-term weight control. The right program can work wonders for motivation and momentum.
A program designed specifically for rapid weight loss or immediate results can provide some clarity in exactly what to do. There's no wondering regarding amounts or types of food.
The main disadvantage is that rapid weight loss programs by nature require significant restrictions of some kind beyond everyday eating. Often it's very manageable -- but food variety and strictness of diet or hunger may be limiting factors for some people. And the body and mind may fight back more (but there are ways of dealing with it: see Sustainability).
If a fast-weight loss regimen ends up being too difficult for whatever reason -- or if you just aren't interested in trying it -- then there's no reason you can't take a more moderate approach of some kind. They work too.
No matter how you lose the weight -- fast or slow -- you have to create certain permanent lifestyle changes to keep weight from returning.
That's one reason why a moderate or slow weight loss approach works well. You build proper habits and behavior from the beginning since that's ultimately what you need to do anyway.
Another benefit is that your body (biology) might not fight back as hard if you take a gradual approach (there are no guarantees of that, though; there aren't definitive studies to prove it).
Fewer drastic dietary changes may also be easier for some people.
Another advantage of more moderate approach -- the way we present it here at LBI -- is that it is very flexible. You choose the tactics and approaches and the level of difficulty.
The main drawback is that progress may be too slow to provide much motivation to continue. Patience is required. It also takes some time to figure out a good mix of tactics that work for you. Yet, once again, you have to admit that patience and long-term habit building is necessary to keep the weight off anyway.
So if you can be patient with potentially slower weight loss and look at the long term perspective, there is a case for more moderate or slower weight loss.
Because each method has benefits, there is a case for using BOTH strategies. How? Here are some examples:
In the end, you'll naturally gravitate toward what works best for you.
Fast Weight Loss Protocol
Slow or Moderate Weight Loss