You don’t usually see lots of media flap about weight loss diets this time of year (too late to lose it for bathing suit season, I guess). But the pandemic’s effect on our collective body weights has upended that. According to some media sources, “we” gained an average of 1.5 pounds for every month of lockdown. What should “we” do about it? This is the never-ending question, but it seems to have taken on a new sense of urgency as it’s being asked by people who haven’t traditionally had this worry on their list.
I’m going to quickly review why human diet studies tend to be less than credible. Then, I’ll review what some of the better studies say about a few of the more talked about diets out there, why the pandemic might offer us some interesting insights into weight gain—and loss, and finally what is the best diet!
The word, “Diet.” Let’s Make Sure We’re on the Same Page.
When the general public hears the word, “diet,” they usually think it has to do with losing weight. However, when nutritionists say the word, “diet,” they’re referring to a specific way of eating, like the Mediterranean Diet ( emphasizing vegetables, fruits, fish, small amounts of other animal protein, and healthy fats, often suggested for promoting heart health), a low-protein diet for kidney disease, and yes, even a gluten-free diet for people with Celiac disease. None of these have anything to do with weight loss. I’ll try to make it clear which I’m referring to below when using the word “diet.”
Studies of Weight Loss Diets
If you’ve read anything I’ve written, you know I tend to be highly critical of human nutrition studies. And as studies go, weight loss studies are among the worst. Why? A few reasons.
When you decide to lose weight, your goal is not usually to lose a couple pounds. Yet, if you read the published results of many diet studies (published in medical journals, that is), oftentimes, the average weight loss was 2 to 5 pounds!
Likewise, if you hope to lose around 15 pounds or more, it’s unrealistic to think you can do it in a month, but most dieting studies last no more than a month or two, at most (which can explain the low weight loss)!
Similarly, when you diet, you don’t usually mean to regain the lost weight after you stop dieting. As such, 99.9% of diet studies measure participants’ weights only at the start and end of the diet period and never follow up with those people 6 months or even a month later. That’s mainly because the studies seldom have any plan to help people maintain their weight loss or continue losing. And that’s the critical difference between successful weight loss and unsuccessful weight loss. Most expert dieters will admit that losing weight is the easy—yes, easy!—part. It’s keeping it off that’s the challenge…which is just one of the reasons “The Biggest Loser©” is such a terrible show. Studies that do measure weight regain tend to show dismal results.
Weight, Weight Loss, and Health
What may be the biggest problem with weight loss studies, though—so big that it deserves its own section—is probably more the fault of the media than of researchers themselves. It’s failing to report how a diet affects people’s overall health. Here’s what I mean.
Weight gain often goes hand in hand with—or causes—unhealthful changes in our bodies. For reasons I won’t go into, blood pressure rises, sometimes to unsafe levels (hypertension); levels of cholesterol and triglycerides in the blood also tend to rise: All of these are major risk factors or markers for heart disease. The chance of developing diabetes also goes way up. If you want to know the detailed reasons, you should talk with your doctor, or you can also send me a message and I’ll be glad to talk with you about it. A good weight loss diet should reverse these trends, either by reducing weight or by introducing healthier eating patterns, or both. But what can happen is that the diet can create more health issues. I know this is counterintuitive, but what we often see is a loss of muscle tissue, or even bone—sometimes a severe loss! Remember, the body has to get its calories from somewhere, and muscle is fair game; the reasons for bone loss are a little more complicated.
When the media reports the results of weight loss studies, they seldom mention health findings, either good or bad. To be fair, most diet studies are too short to expect much in the way of health improvement or worsening. But if you are choosing a weight loss plan, you expect to be following it more than a week or two, so you need to know whether it’s going to help—or harm— your health. Studies of diets like the Mediterranean and Celiac Disease Diets always report the health effects of those diets—because their goal is to improve health. A good weight loss diet study should be no different.
Ok, now to the diets themselves.
Rapid Weight Loss vs. Slow Weight Loss
Is it better to lose weight fast—like with a very low-calorie diet (VLCD, for short: 500 to 800 calories a day) or even bariatric surgery (i.e., stomach stapling)? When I worked in a hospital weight loss clinic, I despaired that some of my clients had already failed stomach stapling, and that most of the rest had already tried some type of VLCD and regained all their lost weight. Yet they all wanted to try another VLCD. And even though my clinic implored our clients to attend weekly classes to learn new ways of eating management and to check in with us as often as possible, most drifted off as soon as they reached their goal weight. And since I lived in a small city at the time, sadly I often saw them regaining their lost weight.
Semi-starvation diets are not meant for the long haul, and they fail to help change the eating and exercise patterns that led to weight gain. A large, recent, high-quality study, the TEMPO trial, did find that people who had lost weight on a 6-month VLCD maintained their weight losses at the end of 3 years at least as well as a control group who lost weight on 12 months of moderate calorie restriction. BUT, the VLCDers had significantly more muscle and bone loss than the slow weight losers, even though the VLCDers were eating mostly protein to help avoid muscle loss. So if you’re considering a VLCD as a way to jump start weight loss, you need to consult with your health care provider, and NEVER undertake a diet like this without regular medical supervision!
Low Carb vs. Low Fat Diets
A few years ago, in one of my blogs, I reviewed the results of the DIETFITS study, an unprecedently well-designed study that found no differences in the effects of low-carb and low-fat diets on weight loss over a year. Being incredibly thorough, they even looked for reasons why some participants lost less than the average amount of weight but didn’t discover anything definitive on that issue. Although I hoped this study would lay the low-carb vs. low-fat issue to rest, the internet and its love for misinformation has made sure to keep it alive.
Low carb diets, which have been around for eons (the Drinking Man’s diet came out in the early 60s, followed by Stillman’s, Atkins, Keto…), are great for losing (mostly water) weight for about 2 weeks. They are not meant as a lifestyle, despite what your trainer and gym buddies tell you (think constipation and true vitamin deficiencies). The theory behind the low carb, ketogenic diet is that when the body can’t get carbs for quick energy, it burns fat, but muscle protein is fair game as well, so add that to the health concerns. A major review in a medical journal two years ago identified a number of serious concerns with low-carb diets.
Personally, I have 2 theories for why low-carb diets seem to work, at least in the short term. 1) high-fat, high-protein foods tend to be more filling than carbs (a theory that has been supported by a large recent meta-analysis of numerous studies) and 2) A cheeseburger is far less appealing without the bun, so by cutting carbs, you unwittingly cut a lot of high-calorie choices—until you discover low-carb bread!
The only people who might benefit from low-carb diets are those with diabetes who, by definition, need to restrict carbs, but not in a way that allows keto breakfast pastries and omits fruits and vegetables! The only low-carb diet worth considering is one that reduces carbs not by omitting vegetables, grains, beans, and nuts but by limiting vast amounts of sugar and refined grains (white bread, pasta, and rice).
And in case you were wondering, a gluten-free diet is not a low carb diet, it is not a weight loss diet, it can have some major health drawbacks, and should not be adopted by anyone who hasn’t been diagnosed with Celiac Disease using valid testing.
Intermittent Fasting vs. Eating 6 (or 8 or 10) Small Meals a Day
People are constantly gushing to me about the weight they’ve lost by intermittent fasting, a practice that involves limiting eating and drinking to some 6 or 8 hours a day. Although elaborate theories abound as to how intermittent fasting affects the body’s metabolism, I maintain that you lose weight because most of us just can’t eat as many calories in 6 hours as we can in 24. But if you’ve found that it’s an effective way for you to limit calories—basically padlocking the kitchen for 18 hours a day—it might be ok. Unless you have diabetes. Intermittent fasting can seriously interfere with your ability to control your blood sugar levels, resulting in hyper- or hypoglycemia—so if you’re diabetic, whether you take insulin or another medication, don’t even consider intermittent fasting without consulting your health care provider!
On the other side of the coin, for some people, hunger is a major factor in why it’s difficult to stick to a weight loss diet, resulting in diet-busting trips to the fridge or the corner variety store. Not that long ago, some nutritionists advocated eating 6 or even 8 small meals a day to avoid hunger. Avoiding hunger can be important, but if you find that your 6 to 8 meals are becoming 6- to 8-course meals, it’s probably time to re-evaluate that habit.
Herbs, Over-the-Counter Medications, Detox Cleanses, and Prescription Medications
Hoping to try one of Dr. Oz’s miracle weight loss potions? I know you were hoping the news would be better by now, but a large recent review found no evidence that any over-the-counter (OTC) diet supplement, including herbal products, works better than a placebo. Oh, you might have heard of a couple that really promote weight loss, but they often turn out to contain dangerous, illegal substances. Same with detox cleanses: Our bodies have organs that are built-in detox systems, known as the liver, kidneys, and lungs, and no toxin has been found that causes weight gain. The only thing these drugs perform miracles for is the bank account of the manufacturer and the folks selling them to you.
What about prescription medications? The current crop of prescription medications for weight loss appears relatively safe when taken with close medical supervision, but these drugs are far from miracle workers. They tend to help weight loss only modestly, and like VLCDs, they don’t help at all with developing different habits, so if you’re considering taking one, do yourself a favor and ask for a referral to a nutritionist who specializes in working with people who want to lose weight and keep it off.
Losing that Pandemic 10 or 20
To sum all this up, please realize there is no one perfect weight loss diet. The best diet for you is the one you, personally, can stick with enough of the time to achieve your goal and keep off the weight you’ve lost, hopefully a plan that includes some physical activity.
If you gained unwanted weight over this past 16 months, use that as a set of clues as to how you gained it and what you need to do to lose it. What changed? Was it the new proximity of your pantry and fridge to your workspace? Were you now buying—and eating—the large economy size of snack foods you’d normally get in 1-ounce portions from the vending machine? Did you take up baking? Were you suddenly cooking at home for the first time but eating larger portions than you’d get if you ate out? Were you now preparing breakfasts, lunches, and snacks for your kids and finishing their leftovers? Stressed over caring for an ill family member? OR, were you no longer going to the gym or even walking to the office, public transportation stop, or coffee shop? Many of the above? Don’t be afraid to try different things to see what works; and I cannot overemphasize the importance of keeping a daily record of food intake and your exercise routine. I remember distinctly many years ago when one of my clinic patients and I figured out through food records that a lot of her unnecessary calories came from the “Giant Slurpee” she got every day at the local 7-11 when driving to work, but she couldn’t quit stopping there. I suggested she find another route to work. She hadn’t thought of that. Sometimes the obvious just eludes us.
As pandemic restrictions lift, you can hopefully start to get back on track. But give yourself a break and start slowly: One of the most concerning things I’ve read in the past week is this summer’s alarming rise in a health condition called rhabdomyolysis, a serious muscular breakdown in otherwise healthy people that can be caused by ramping up exercise too quickly (and exacerbated by certain supplements). Check out some of the suggestions here for finding and staying with a plan. And if overweight is a long-term struggle for you, you might really relate to this piece in the Annals of Family Medicine that came out just before last year’s shutdown; I encourage you to share it with your primary care provider.
Finally, if you have interesting insights or experiences to share about the pandemic and weight, or if you have questions about weight loss diets I haven’t mentioned, please feel free to email me or respond on Facebook, Instagram, or my site!
Next time: Are probiotics good for anything?