The 8 Worst Weight-Loss Diets of 2023

Every year, millions of Americans go on a diet, spending more than $72 billion on weight-loss products in 2021, according to market research company Research and Markets. But even the most popular diets don't necessarily guarantee success.

According to April 2020 research in the ‌BMJ‌, even when people experience moderate weight changes after starting a new diet, by a year later, any weight loss or improvements in heart health "largely disappear."

Some may even do more harm than good. Dieting has been linked to development of eating disorders, depression and irritability, and repeatedly losing and regaining weight is associated with an increased risk for diabetes and strain on the heart, according to September 2020 research in ‌Cureus‌.

That's why, if you're looking to follow an eating plan, it's important to work with a health professional who can help you find the right one for you. Lists are made to help you on your search, but it can take trial and error to find your own best weight-loss plan.

One such list that aims to help you do just that is the annual best diets ranking from U.S. News & World Report, which evaluates fad diets as well as eating plans with more staying power, according to a panel of health experts.

Historically, U.S. News has included some of the worst weight-loss diets as a way to discourage people from trying them. This year, they've opted to exclude them entirely, meaning they likely will not help with long-term weight loss.

For healthy weight loss in 2023 and beyond, steer clear of these plans.

The Gut and Psychology Syndrome Diet (aka GAPS) is based on establishing a link between your digestive system and brain, according to the GAPS website. Unlike other diets, the goal of this regimen is to help improve gut health through diet, supplements, detoxification and lifestyle changes.

While there is growing interest around the link between gut health and weight, there isn't strong evidence supporting any best way to improve gut health for weight loss.

Plus, this strict elimination diet can be tough to stick to: It involves cutting grains, dairy, certain legumes and starchy vegetables, among other nutritious foods, according to the diet's website.

The Autoimmune Protocol Diet (also known as the Autoimmune Paleo Diet) is an extension of the paleo diet that aims to reduce inflammation and alleviate autoimmune disorder and bowel disease symptoms, according to a November 2017 study in ‌Inflammatory Bowel Diseases‌.

The goal of the AIP Diet is to help pinpoint food allergies and intolerances by eliminating a variety of foods, including nightshade vegetables (eggplant, tomato), grains, dairy, eggs, legumes, nuts and seeds. Instead, the plan focuses on organ meats, bone broth and fermented foods and oils.

Because the diet involves strict elimination, weight loss can be a byproduct, though it's far from the best way to go about shedding pounds. The real goal of the diet is to identify intolerances and allergies, but you should talk to your doctor or a dietitian before trying it for that reason.

The Acid Alkaline Diet suggests eating acid-forming foods, like beef, can throw your pH levels out of balance, resulting in poor overall health, according to U.S. News & World Report. As we're constantly putting acidic foods in our systems, our bodies are too preoccupied with removing the acidity to support good health, the diet suggests.

This diet is especially challenging, as it requires choosing foods that are either neutral or alkaline (7 to 14 on the pH scale). Generally, this involves eliminating meat, poultry, dairy and grains, focusing instead on healthy fats, fruits, vegetables and legumes.

Like other diets on this list, this restrictive plan could easily lead to increasing cravings or overating. Not to mention, it can be time-consuming to plan, shop for and prepare meals that fit the pH parameters.

The Dukan Diet focuses on protein intake, rather than calories, as the key to weight loss, according to U.S. News & World Report. Like Atkins and keto, this diet is based on the idea that cutting carbs forces your body to burn fat. However, unlike other low-carb regimens, Dukan focuses more on increasing protein consumption.

The Dukan Diet can lead to short-term weight loss, but it's an extremely restrictive plan. While you can eat an unrestricted amount of protein and veggies, all other food groups are either curtailed or cut completely.

Based on U.S. News' criteria, this diet promises weight loss in an unhealthy and unrealistic timeline.

The Whole30 diet claims to help eliminate cravings, improve energy and sleep and promote weight loss, according to the Whole30 website. This diet involves eliminating added sugar, alcohol, grains, legumes, dairy, sulfites and baked goods for 30 days. After the 30 days are up, participants can reintroduce certain food groups slowly, with the goal of identifying which foods make them feel better or worse.

Although the Whole30 diet isn't particularly unsafe, it is restrictive and requires high levels of commitment to actually "work," according to U.S. News & World Report. Closely following Whole30 requires daily planning and meal preparation in order to successfully identify which foods do and don't work for your body, and that level of commitment is too much for a lot of people.

As it sounds, the goal of the Fertility Diet is to promote overall reproductive health, according to U.S. News & World Report. By increasing intake of healthy fats, whole grains and plant protein, while limiting refined carbs and red meats, the Fertility Diet suggests followers can improve their chances of getting pregnant.

Weight loss may sometimes be a side effect of the diet, as it's mostly lower in carbs. But while this diet is generally easy to follow, there's no evidence to suggest it can actually improve your fertility or ability to get pregnant, per Harvard Health Publishing.

While the Acid Alkaline Diet recommends eating according to pH level, the Glycemic-Index Diet encourages choosing foods based on your blood sugar levels, according to the Mayo Clinic.

The glycemic index is a scale that ranks carbohydrate-rich foods according to their effect on blood sugar levels, per the Mayo Clinic. So, the goal of the Glycemic-Index Diet is to prioritize carbs that are less likely to cause blood sugar spikes.

As with most of the diets on this list, weight loss may be a side effect, considering it involves cutting many high-sugar foods, according to the Mayo Clinic, although there's no promise you'll actually lose weight. Plus, there are plenty of healthy fruits (like watermelon and banana) that are technically on the higher end of the glycemic index scale.

The Sirtfood Diet is a three-week eating plan that's split into two phases, according to the Sirtfood website. The first phase involves cutting your total calories for seven days and increasing your green juice intake, along with other diet-approved foods, like fruits and walnuts.

The second phase is two weeks long with no specific calorie restrictions. During this time, you eat about three meals of sirtfood (like green tea, kale and blueberries, which purportedly activate sirtuins, proteins that some research has linked to regulating inflammation and burning fat) along with one green juice per day.

While this diet does promote plenty of nutrient-rich foods, it also encourages a pretty restrictive meal plan that cuts out plenty of other nutritious foods. Although you may see some initial weight loss due to calorie cuts, it's a pretty unsustainable routine for the long-term.