True or False? Losing Your Weight Slowly Will Yield Better (Long-Term) Results Than Rapid Weight Loss - Another Common Weight Loss Myth Debunked by Science?!

With adequ. protein and nutrients "crash"- beats "low and steady" -dieting. In the obese that's almost certain, in athletes more experimental evidence are needed.

You will have heard and read that rapid weight loss will make you lose muscle and set you up for weight regain aka the "Yo-Yo effect". As a SuppVersity reader, you know that things are not as simple as that. While some studies appear to support this urban myth others suggest that the exact opposite may be the case.

A 2014 study by Purcell, Sumithran, and Prendergast that was published in the venerable scientific journal The Lancet for example, showed that rapid weight loss on a very low calorie diet leads to better long-term outcomes than gradual weight loss on a much less restricted diet.

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That's a results of which I feel that it is important enough to re-address ii in its own SuppVersity article. After all, the "slow and steady" advise is still ubiquitous, both in the mainstream and in the health and fitness community. In said study, Purcell et al.

"aimed to investigate whether the rate of weight loss affects the rate of regain, and whether weight lossinduced changes in circulating appetite-mediating hormones and subjective appetite are affected by the rate of weight loss" (Purcell. 2012).

To this end, the researchers from the University of Melbourne conducted a two-phase, non-masked, randomized controlled trial. The study participants were recruited through radio and newspaper advertisements and word of mouth in Melbourne, Australia.

• Inclusion criteria were healthy men and women aged between 18–70 years who were weight stable for 3 months and had a BMI between 30.0–45.0kg/m². 
• Exclusion criteria included use of a very low energy diet or weight loss drugs in the previous 3 months, contraceptive use, pregnancy or lactation, smoking, current use of drugs known to affect body weight, previous weight loss surgery, and the presence of clinically significant disease (including diabetes).

Eligible participants were randomized into 2 different weight loss programs — a 12-week rapid program or a 36-week gradual program —using a computer-generated randomization sequence with a block design to account for the potential confounding factors of age, sex, and body mass index (BMI). Investigators and laboratory staff were blind to the group assignments.

Figure 1: Overview of the study design (Purcell. 2014)

Both, the subjects on the rapid and the gradual weight loss program had the same simple goal: "Reduce your body weight by at least 12.5%." The way the subjects were supposed to achieve this weight loss was yet completely different. For phase 1 of the study (until 12.5% weight loss), the following interventions were prescribed:

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  Better ZERO than Some Food? Study Suggest Just That! Learn more.

  Rapid weight loss: Participants in the rapid weight loss group replaced 3 meals a day with a commercially available meal replacement (Optifast, Nestlé Nutrition) over a period of 12 weeks (450–800 kcal/day). 
• Gradual weight loss: Participants in the gradual group replaced 1 to 2 meals daily with the same supplements and followed a diet program based on recommendations from the Australian Guide to Healthy Eating for the other meals over a period of 36 weeks (400–500 kcal deficit per day).

Both groups were given comparable dietary education materials and had appointments every 2 weeks with the same dietician. Participants who achieved 12.5% or greater weight loss were eligible for phase 2. In phase 2, participants met with their same dietician at weeks 4 and 12, and then every 12 weeks until week 144. During appointments, the dietician assessed adherence based on participants' self-reported food intake, and participants were encouraged to partake in 30 minutes of physical activity of mild to moderate intensity. Participants who gained weight were told to reduce their energy intake by 400–500 kcal in order to get back on the weight loss track.

High(er) protein intake (1.2-1.4g/kg) are a way to make very low calorie diets, here fasting vs. protein modified fasting, more effective (Iselin. 1982).

Wait, but what about all the other studies? Well, in their research review, Purcell et al. "found no randomised clinical trials" which even investigated the difference. Practically speaking, this means that the general consensus which is that weight loss should happen gradually and at a rate of 0.5 kg per week is more or less arbitrary (from a science perspective). If you look more closely, though, you will find acute weight loss studies without appropriate follow up you could use as evidence in favor of dieting down slowly - mostly for decreased muscle loss in low (=RDA) protein diet scenarios, though. With adequate protein intakes, said studies yielded very different results - e.g. protein-modified fasts (see Figure | Bistrian. 1977; Iselin. 1982).

To assess the success of the diets, the scientists used the mean weight loss that was maintained at week 144 of phase 2 (primary outcome), the mean difference in fasting ghrelin and leptin concentrations measured at baseline, end of phase 1 (week 12 for rapid and week 36 for gradual), and at weeks 48 and 144 of phase 2, as well as the overall changes in weight, BMI, waist and hip circumferences, fat mass, fat free mass, ghrelin, leptin, and physical activity (secondary outcomes).

Figure 2: Percent of participants achieving the weight loss target in phase 1 completers (left) and all subjects including the losers who didn't complete the full study - that the right figure shows even greater differences actually supports the superiority of the rapid vs. gradual weight loss regimen (p = 0.0001 | Purcell. 2015)

The overall message of the results was clear, the "rate of weight loss does not affect the proportion of weight regained within 144 weeks" (Purcell. 2014). The same goes for the implication that "[t]hese findings are not consistent with present dietary guidelines which recommend gradual over rapid weight loss, based on the belief that rapid weight loss is more quickly regained" (ibid).

Figure 3: Relative changes in measures body composition (left) and activity from pre- to follow up (Purcell. 2015).

But this wouldn't be the SuppVersity if we didn't go beyond the mere averages for the main study outcomes. So, let's take a look at the actual changes from the pretest to the follow up in Figure 3. What do you see? Yes, the rapid weight loss group had better (albeit not significantly better) results in everything and that despite the fact that they didn't increase their physical activity (see Figure 2, right). So let's not forget that this information that's missing from the abstract, when we're discussing the "bottom line" to this article in the following paragraphs.

So, fast and furious (weight loss) is always the better choice? I would not necessarily say so, but as Martin et al. point out in a comment on Purcell's study we cannot simply ignore that (a) fewer participants dropped out early in the rapid weight loss group than in the gradual weight loss group, and that (b) during phase 1, more participants in the rapid weight loss group achieved the target weight loss of 12.5% than in the gradual weight loss group (81% vs 62%).

It would be stupid to blindly stick to the mantra that "slow and steady is always better" if evidence from well-designed clinical human trials says the opposite. Specifically, if we also take into account that ...

• 

  Nacker's re-analysis of the TOURS study shows similar results. Subjects who lost weight fasted had the best short+long-term results.

  the subjects who had far less time to achieve the same energy deficit, showed no evidence of relative increases in the adaptational processes like higher levels of the hunger or the "hunger hormone" ghrelin, which are believed to hinder long-term weight loss success
• despite the fact that both groups regained a similar amount of weight, the subjects in the rapid weight loss group, who used a very low calorie diet in phase 1, still had better outcome in both, the short and long run (n.s. difference), compared with those in the gradual weight loss group, who used a moderate caloric deficit.

There's thus no reason to question Purcell's conclusion that very low calorie diets can encourage adherence, weight loss, and retention. In that, it is interesting to point out that...

• very low calorie diets restrict food variety which can actually promote greater satiety and less food intake compared with diets that have more food variety (Rolls. 1984), and
• very low calorie diets are not complex to follow, have simple rules, limit choice,  and essentially eliminate the need for participants to measure or estimate portion size, an endeavour associated with error (Martin. 2007)

In addition, the rapid weight loss success on very low calorie diets is, as Martin et al. rightly point out, "presumably intrinsically rewarding and builds self-efficacy because behaviour change is proximally associated with a large and meaningful reward" (Martin. 2014).

Chronic Energy Deficits Make Athletes Fat - The Longer You Starve, the Fatter You Get. No Matter What the Calories-in-VS-Calories-Out Equ. Says

If the known and manageable downsides, which are a potential lack of adequate protein and essential micronutrients, or constipation are taken care of and the length and frequency of the interventions is reasonable (e.g. 8-12 weeks depending of the amount of superfluous body fat with 4-6 weeks breaks between cycles), there's no reason to doubt that rapid weight loss on adequately designed very low calorie diets will yield better results than the "slow and steady" approach in the obese. Evidence from studies in athletes is mixed: On the one hand, there are profound detriments from longterm-deficits and no harm from appropriately planned short-term severe calorie restriction. On the other hand there are potential performance decrements (Mero. 2010) without negative effects on body composition and a single study suggesting that deficits of only 9kcal/kg (vs. 15kcal/kg) may allow for muscle gains even while dieting (Garthe. 2011) and thus be superior to taking the "fast track".

So, while it appears quite clear that obese individuals can benefit from losing weight rapidly, there's a paucicity of evidence for athletes and very lean individuals... but even if we had these study, this wouldn't change that what's optimal for you will depend so much on your personal preferences, your lifestyle, your sport, your current body fat levels etc. that there's no general one-size-fits-it-all recommendation. What's important, though, is not to get stuck in the "ONLY SLOW AND STEADY WILL WORK" mantra. Especially if you're not ripped (yet) doing the exact opposite and doing it cyclically may be the better choice | Comment on Facebook!!

References:

• Bistrian, B. R., and Mindy Sherman. "Results of the treatment of obesity with a protein-sparing modified fast." International journal of obesity 2.2 (1977): 143-148.
• Garthe, Ina, et al. "Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes." International journal of sport nutrition and exercise metabolism 21 (2011): 97-104.
• Iselin, Hans U., and Peter Burckhardt. "Balanced hypocaloric diet versus protein-sparing modified fast in the treatment of obesity: a comparative study." International journal of obesity (1982).
• Martin, Corby K., et al. "Empirical evaluation of the ability to learn a calorie counting system and estimate portion size and food intake." British Journal of Nutrition 98.2 (2007): 439-444.
• Martin, Corby K., and Kishore M. Gadde. "Weight loss: slow and steady does not win the race." The Lancet Diabetes & Endocrinology 2.12 (2014): 927-928.
• Mero, Antti A., et al. "Moderate energy restriction with high protein diet results in healthier outcome in women." J Int Soc Sports Nutr 7.4 (2010): 1-11.
• Nackers, Lisa M., Kathryn M. Ross, and Michael G. Perri. "The association between rate of initial weight loss and long-term success in obesity treatment: does slow and steady win the race?." International journal of behavioral medicine 17.3 (2010): 161-167.
• Purcell, Katrina, et al. "The effect of rate of weight loss on long-term weight management: a randomised controlled trial." The Lancet Diabetes & Endocrinology 2.12 (2014): 954-962.
• Rolls, Barbara J., P. M. Van Duijvenvoorde, and Edmund T. Rolls. "Pleasantness changes and food intake in a varied four-course meal." Appetite 5.4 (1984): 337-348.