It’s taken almost as a matter of faith in the fitness world that slower rates of weight loss are superior to faster rates and that rapid fat loss always cause faster rates of regain and poorer long-term results. And while there is certainly data to support that, we might ask if it is always the case. You can probably guess by the title of this article that it’s not.
Note: Most research studies still tend to focus on weight loss despite the fact that fat loss and changes in body composition is a far greater metric of change. For that reason I will be switching back and forth from fat and weight loss throughout the article.
Slow vs. Rapid fat Loss
While it’s taken as axiomatic that rapid fat loss is always inferior, there is a far amount of data that actually suggests the opposite. That it, studies routinely show that a FASTER or GREATER initial weight loss is associated with BETTER long-term weight maintenance rather than worse.
However, against this notion speaks numerous post hoc analyses of weight loss intervention studies showing that a greater initial weight loss, usually achieved in the first 2-4 weeks of treatment, is associated with a better long-term outcome, i.e. a sustained weight loss 1-5 years later.
In an older 1995 study, for example, Astrup showed that the group of dieters who had lost the most weight at week 36 (17.7 kg/39lb vs. 9.8kg/22lb) had maintained more a greater weight loss 2-5 years later. Specifically the rapid weight loss group was still 7.1 kg/15.6 lbs down vs. a 2.8 kg/6.2lb weight GAIN in the slower weight loss group. So the rapid weight loss group was still 21 lbs ahead.
Already that seems to throw the dogma on its head, raising the question:
How Can Rapid Fat Loss Be Superior?
Analyzing study data after the fact can be problematic since it’s easy to confuse correlation with causation. Here’s a good example. A lot of observational research has found that people who skip breakfast or drink diet soda are overweight.
And one conclusion that is often reached is that skipping breakfast or drinking diet soda CAUSES weight gain. But this is usually a case of reverse causation. Specifically when people gain weight they often start skipping meals or drinking diet soda. Weight gain causes the habits rather than the other way around.
In the case of rapid fat loss, we can’t automatically conclude that rapid fat loss is causing the superior long-term results because that isn’t what the study was testing. We know that some people have an easier time physiologically losing weight/fat than others. There are differences in genetic, environmental and hormonal factors that can all contribute.
Perhaps people who lose weight most easily (i.e. get faster rapid fat loss) are the ones who are biologically more likely to keep it off in the long-term. Perhaps the people who lose weight the fastest initially are simply more dedicated to their goal to begin with? That alone would predict better long-term weight maintenance.
But in both cases it isn’t the rapid fat loss causing the superior long-term results. Rather it’s a third independent variable impacting on both.
That’s why you have to do controlled studies in this regard, where you put two groups on different rates of weight/fat loss to see what happens in the long-term. There is surprisingly little work in this regard.
Is Rapid Fat Loss Actually Superior?
For this reason it’s crucial that controlled studies, where the rate of weight loss is manipulated be performed. Not a lot of work has been done in this area but what work has been done is certainly supportive of the idea.
In one study, subjects were placed on either a very low calorie diet or a conventional diet so that they would lose the same amount of weight over different times frames (8 vs. 17 weeks). Both groups lost 13.6 kg but, of course, the rate of weight loss was double in the very low energy group. Weight loss maintenance was higher by 2.4 kg at one year and 3 kg at two years although this wasn’t statistically significant between the two groups.
The paper concluded:
Ad lib, low fat, high carbohydrate diet was superior to fixed energy intake for maintaining weight after a major weight loss. The rate of the initial weight loss did not influence long term outcome.
So it was no better. However, to quote again from the first reference linked above:
At least this study does not support that a rapid weight loss influences long-term outcome adversely.
And even that goes against the common dogma. It wasn’t better but it didn’t cause more rapid rates of weight gain or worse long-term results.
Fat Loss Approaches are Usually Multi-Factorial
Now, a problem with many dieting studies is that the often use multi-factorial approaches to weight loss and this can make it difficult to isolate out what’s doing what. For example, some studies will examine diet with behavioral therapy or exercise, or diet with or without diet drugs, or some combination of all of those. Figuring out what’s driving what can be difficult.
Maybe it was the diet, maybe it was the drugs, maybe it was the behavioral intervention, maybe it was the combination of everything tested. I vaguely recall one paper that literally threw everything but the kitchen sink at folks for weight loss. Diet, exercise, behavioral interventions, follow-ups, maybe drugs. You name it and they did it. And the results were incredible. Which isn’t surprising, even if it’s not really practical.
But this multi-factoriality aspect of science explains at least some of the research showing a worse result from very low calorie diet approaches.
Most Rapid Fat Loss Plans are Stupid
There are a lot of rapid weight and fat loss plans out there. This includes commercial diet centers along with clinical diet trials. And, honestly, most of these do fail spectacularly. But they are also invariably badly set up, sharing a number of similar characteristics that make them assured to fail.
The Diet Component
First and foremost they tend to be set up around pre-packaged liquid nutrition. This is convenient but this does nothing to change people’s nutritional habits in the long-term. They can generate stunningly rapid weight loss but they don’t help with long-term maintenance.
As I clearly state in my Rapid Fat Loss Handbook:
I will be the first to admit that just measuring out powders makes it extremely easy to
control food intake….The problem in my mind is that, while this approach to dieting generates amazing weight/fat loss in the short term, it does nothing to teach or retrain overall eating habits in the longer term.
Basically, to have any chance of succeeding in the long-term, any diet approach (whether slow or fast) must contain an element of nutritional education. Along with generating quick weight loss, the diet should work to help the person learn good long-term eating habits.
The Exercise Component
This would be more accurately described as the lack of exercise component. Because almost all rapid weight loss programs either don’t include exercise or actively recommend against it. Now, there’s no doubt that exercise has a relatively minimal effect on total weight and fat loss for most people.
Simply, at realistic levels, most people can’t do enough for it to matter. The number of calories burned simply pales to the amount that can be changed by adjusting the diet. That said, proper exercise can ensure that lean body mass is not lost. This indirectly increases fat loss and lowers the risk of a post-diet bodyfat regain, especially for leaner dieters.
That said, endless research shows that exercise plays its primary role for weight-loss maintenance. Simply, any diet or training program that doesn’t set the person up with tools for long-term maintenance is a bad one. Because it is factually setting someone up for failure.
The Rapid Fat Loss Handbook
So what we see from the above is that a diet based around whole foods which includes exercise is the key to making rapid fat loss workable. And, as you’d expect this is exactly how I set up my Rapid Fat Loss Handbook. The program is based around low-calories with the majority coming from whole food rather than dietary supplements.
The base diet meets all of the body’s essential nutrient requirements which are dietary protein, essential fats and the vitamins/minerals. When people move out of the diet, they simply add foods back to that baseline diet so it’s working to retrain long-term eating habits.
As well, exercise (primarily weight training with only small amounts of cardio required or recommended) is recommended during the diet, with an increase in aerobic type activity when the dieter either moves into maintenance or a moderate type of dieting approach; again this is consistent with the research on the topic. I probably spend more time discussing maintenance than I do the diet itself since, honestly, long-term maintenance is usually the harder bit for most people.
Everybody can lose weight. It’s keeping it off that is the difficulty.
Many has also found that a rapid fat loss approach is a great way to kickstart a more moderate diet. I think a lot of this is psychological. For folks with a lot of fat to lose, the slower rates of fat loss that occur with more moderate approaches can be disheartening. Getting some rapid fat loss right up front before moving back to a more moderate approach can provide the best of both worlds.
[Very low calorie diet] with active follow-up treatment seems to be one of the better treatment modalities related to long-term weight-maintenance success.
In this context, follow-up treatment included behavior therapy, nutritional education and exercise. A rapid fat loss approach followed for 2-4 weeks before moving into maintenance may represent a nearly ideal compromise in this regards. The dieter can get some rapid fat loss and instant gratification, force-altering their eating habits, before moving back towards a more moderate approach for the long-term?
Is Rapid Fat Loss Always Better?
As much as research supports rapid approaches being better in some ways (or at least not worse), that doesn’t make them appropriate for everyone. People who have shown a repeated pattern of alternating extreme (usually poorly set up) diets followed by rapid weight regain or binge type eating invariably do very poorly with extreme diets. They may do stunningly while they are on the diet itself but, as soon as the diet ends, they flip-flop to the other extreme.
For those individuals, I would at most suggest trying a properly set up rapid fat loss plan if they must. Again that means whole foods and a proper exercise program. None of this chicken broth, detox, fasting bullshit. Whole foods, moderate exercise and see if it works. If not, they should try something a little more moderate.
Irrespective of that, the dogmatic idea that rapid fat loss is always the wrong approach to dieting is not only not supported by research but contradicted to at least some degree. Done correctly it’s not worse and may even be superior in some cases.