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Evidence Based

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This article contains scientific references. The numbers in the parentheses (1, 2, 3) are clickable links to peer-reviewed scientific papers.

What’s the Best Way to Lose Weight? A Look at the Science

Written by Dr. Michael Ruscio, DC on January 4, 2019

Written by Dr. Michael Ruscio, DC on January 4, 2019 — Reviewed by Joe Mather

I’ve found a review that delves into some of the current research literature related to these four popular weight loss strategies:

• Juice fasting or detoxification diets
• Intermittent fasting
• The paleo diet
• High intensity training

The beauty of a review like this is that it provides an overview of the current body of scientific evidence and is much more reliable than any single study.

So, let’s have a look at what the authors discovered about each weight loss strategy.

Juice Fasting and Detox Diets for Weight Loss

This category includes any short-term diet where all meals are replaced with juices and/or supplements. This includes commercial diet plans that prescribe meal replacement products. In some cases, laxatives and/or saunas are also prescribed. These diets typically last from 2 to 21 days and involve severe calorie restriction. Diets in this category may range from 400 to 1200 calories per day.

The authors of this review were unable to find any randomized controlled trials conducted with humans for these types of diets. This means that little is known about the effectiveness and risks of juice fasting and detoxification diets.

Because of the scarcity of data, the authors reviewed research about severe calorie restriction. In one study, women who followed a diet of 1200 calories per day had raised stress hormones, including cortisol. Increased cortisol has many negative effects. One effect is appetite stimulation.

So, while you may lose weight fast with severe calorie restriction, rebound weight gain is a real risk.

The authors also searched for individual reports of adverse effects of juice fasting and detox diets. They found one horror story where 60 people died after consuming a low-calorie liquid formula made from slaughterhouse by-products. Other adverse effects reported were manganese overdose, laxative abuse, electrolyte abnormalities and renal failure.

The Bottom Line on Juice Fasting and Detox Diets for Weight Loss

Rapid short-term weight loss is possible with these diets because of extreme calorie restriction. But consuming so few calories raises stress hormones, which can lead to binge eating and rebound weight gain.

The potential health risks of these diets are not well understood. It’s also important to remember that the quality of commercial meal replacement formulas varies widely. Some low-quality diet products may pose health risks.

Overall, this approach is not recommended for sustainable, long-term weight loss.

Intermittent Fasting for Weight Loss

Intermittent fasting is an eating pattern that involves periods of fasting (usually 16 to 48 hours) alternated with periods of normal eating. There are many different approaches to scheduling fasting and non-fasting periods.

Research into intermittent fasting and weight loss in humans is limited to a few small-scale human trials. Much of the research is designed to compare intermittent fasting with traditional calorie-restricted diets, where the overall daily caloric intake is equal. There have been no studies to compare different intermittent fasting schedules.

Like other weight loss diets, intermittent fasting works because it reduces caloric intake. When compared to traditional calorie-restricted diets, some studies show intermittent fasting has similar weight-loss outcomes. However, one study in a group of overweight women showed greater body fat reduction and improved insulin sensitivity for the intermittent fasting group.

Other research into intermittent fasting shows that metabolic improvements may occur during the fasting period. Some subjects also report a heightened level of alertness during the fasting period.

The Bottom Line on Intermittent Fasting

Intermittent fasting appears to help with weight loss by decreasing overall caloric intake. But is it more beneficial than traditional calorie restricted diets? The evidence here is conflicting. Some evidence suggests that intermittent fasting may have superior metabolic benefits. However, further research is needed.

If you want to try intermittent fasting, experiment with different fasting schedules to find an approach that works for you. Keep in mind that longer fasting periods may increase your stress hormones. This may lead to binge eating. Find an intermittent fasting pattern that you can sustain over the long term.

Paleo Diet for Weight Loss

The paleo diet was designed to mimic the human diet in the Stone Age. It emphasizes non-processed foods such as vegetables, fruit, meats, poultry, fish, eggs, nuts, and seeds. Cereals, grains, legumes and dairy are usually prohibited.

At least nine clinical trials have shown short-term benefits for the paleo diet.   Benefits include:

• Weight loss
• Reduction in waist circumference
• Increased glucose sensitivity
• Improved lipid profiles

As with the other weight loss strategies, most of the studies into the paleo diet are small and short-term. The largest trial included 70 post-menopausal, obese women. This study compared the paleo diet with the Nordic Nutrition Recommendations Diet over 24 months. At the end of six months, the paleo diet group experienced significant fat reduction and weight loss. However, there was no difference between the two groups at 24 months.

Some side effects have been reported from the paleo diet. These include weakness, diarrhea, and headaches. Also, since dairy is restricted, the authors point out that there is a potential for lowered calcium intake with impacts on bone density.

The Bottom Line on the Paleo Diet

With the paleo diet there are clear short-term benefits for weight loss and metabolism. But over the long term, the paleo diet may not result in better weight loss outcomes than other healthy diet plans.

One of the common critiques of the paleo diet is that it can be an expensive diet to follow. Some people find it too time consuming to prepare meals from unprocessed food.

High Intensity Training (HIT) for Weight Loss

HIT is an exercise strategy that involves short bursts of maximum-intensity activity alternating with periods of rest. HIT differs from moderate intensity training (MIT) which involves sustained moderate levels of activity (such as typical cycling or jogging).

There have been several randomized controlled trials (RCTs) to study the weight loss effects of HIT. Research suggests that HIT is an effective strategy for weight loss that can be accomplished in surprisingly short periods of time.

One study compared HIT with MIT for 28 obese and overweight men.

• The HIT group performed 20-minute HIT sessions each week, for a total of one hour per week.
• The MIT group performed 45–60 minutes of moderate cycling, for a total of five hours per week.

After six weeks, participants in both groups showed:

• Similar improvements to insulin sensitivity
• Similar reductions in blood lipids
• Similar decreases in body fat
• Differences in cardiovascular fitness. Both groups showed improvements, however the MIT group had greater improvements.

The Bottom Line on High Intensity Training

HIT has considerable weight loss benefits and requires much shorter time commitments than traditional exercise programs.

HIT may be less feasible for people with physical limitations, including some obese individuals.

Weight Loss Strategies – What You Need to Know

One conclusion from this review seems to be that calorie restriction is most likely the foundation for all dietary approaches to weight loss. So, no matter the approach you choose, calorie restriction is still the key. Moderate approaches to calorie restriction are more effective in the long term. Severe calorie restriction can be counter productive, leading to binge eating and weight gain.

While there is no clear evidence that intermittent fasting and the paleo diet are superior to traditional weight loss approaches, they are both solid choices for weight loss and improved metabolic health. Based on my clinical experience, I do recommend the paleo diet as it has many additional health benefits that are not in the scope of this review. Whatever weight loss diet you choose, look for an approach that is healthy and sustainable over the long term.

HIT provides an efficient way to getting the most out of short workouts. Putting less time into your exercise routine may help to keep you motivated. Give HIT a try if you are physically able to work out at maximum intensity.

Keep in mind that it is possible to combine these approaches.

It’s always good to have more than one tool in your weight-loss tool belt:

• The paleo diet provides a great template for making healthy food choices. It may be especially effective for boosting short-term weight loss.
• Intermittent fasting provides a pattern of eating that helps achieve moderate calorie restriction.
• HIT gives you a quick and efficient exercise routine.

Each of these approaches could play a role in your overall weight loss strategy.

Learn more about healthy weight loss: Which Comes First? Healthy Gut or Weight Loss?

What do you think? I would like to hear your thoughts or experience with this.

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