Everything you need to know about these 5 popular diets

Should you try low-sugar, paleo, keto, intermittent fasting, or low-carbon eating? Our nutritionists weighs in.
Published 6 January 2020 | Updated 6 May 2024

If you've scrolled through your online feeds recently, chances are you've come across posts hyping the latest, cleanest, hottest, healthiest, and most life-changing way to eat EVER. Curious if these trends are legit or just a load of BS? Registered Dietitian, Jaclyn London, MS, RD, CDN, weighs in:


1. Low-sugar diet


What it is: Most low-sugar diets focus on reducing added sugar from your meals.

Is it healthy? Yes. Eating a low-sugar diet or simply cutting back on your sugar intake may help you reach your weight-loss and wellness goals and decrease long-term risk of chronic disease, including type II diabetes, heart disease, and some lifestyle-related cancers.

After all, many people tend to overconsume sugar—sometimes without even knowing it. That’s because sugar is added to many foods beyond desserts, like beverages (including soft drink, sports drinks, sweetened tea, and flavoured coffee), crackers and chips, and even some healthy-sounding products like protein powder.

Added sugars can also sneak into foods that seem healthy, such as processed forms of fruits and vegetables. Take, for instance, fruit juices, smoothies, sweetened dried fruits, and sugary purees used in sauces and condiments—they can contain high levels of added sugar.


How to try it:

  • Choose whole foods in their natural state. That means oranges instead of orange juice, tomatoes over tomato sauce, baked potato rather than potato chips, etc. At WeightWatchers, all foods can fit into your Points Budget. But because unprocessed ingredients are either ZeroPoint foods (which you don’t have to weigh, measure, or track) or are lower in total Points than their processed counterparts, your budget will go further if you choose whole foods prepared in ways that are nourishing for your taste buds and your body.
  • Read labels and check for hidden sources of added sugar. Look for words like “tapioca syrup,” “evaporated cane juice,” “brown rice syrup,” “agave nectar,” “maple syrup,” “honey,” “molasses,” or “date syrup,” to identify the sources of sugar in a product. Often, foods with higher amounts of these ingredients will be higher in Points, so consider how you’ll fit them into your daily budget before you load up your shopping trolley.
  • If you enjoy dessert, factor it into your Points Budget. Since sugar plays a role in calculating a food’s Points value, the program is structured to encourage a gradual shift toward a lower-sugar eating pattern. In essence, this means there's no need to cut out dessert entirely! While you can allocate your Points towards sweet treats, the program naturally guides you towards options with less added sugar. To manage your budget and reduce overall sugar intake, you might choose to save Points for a desired brownie later by passing on the sweetened latte you usually have at breakfast time.


2. Plant-based diet

(aka low-carbon diet or climate diet)


What it is: This approach to eating focuses mostly (or only) on foods from plant sources. It often calls for eating less meat, dairy, packaged products, and imported products; many experts believe this will reduce your carbon footprint and slow the rate of climate change to benefit the planet.

Is it healthy? Yes. “Overall, plant-based diets are rich in important antioxidants that help your body stay healthier, particularly because they’re loaded with vitamins and key minerals,” London says. They also contain immune-boosting nutrients like vitamin C (ascorbic acid), vitamin A (carotenoids), and vitamin E, as well as zinc, selenium, and copper—plus compounds such as flavonoids, which are powerful antioxidants associated with boosting immune function.


How to try it:

  • Think “more produce, more often.” Plant-based eating is just that—plant based, not necessarily vegan or vegetarian, if that’s not your bag. So while you don’t have to eliminate any food groups for adherence, you can consider ways to add more vegetables (and fruit!) to your day. Try including an extra veggie side at dinnertime or adding a piece of fruit to your lunch. You’ll reap the benefits in nutrition, and it’ll help you feel fuller for longer. Bonus: On WW, fruits and non-starchy veggies are ZeroPoint foods—so packing them into your day won’t impact your budget.
  • Fill your shopping trolley with plant-based protein. Legumes like beans, lentils and chickpeas, are typically lower in saturated fat and sodium than red meat and processed/deli meats. (They tend to be cheaper, too.) Stocking up on these staples is smart for your body, your wallet, and the planet.


3. Low-carb or ketogentic diet


What it is: Reduced-carbohydrate diets, such as the ketogenic diet, have become increasingly popular in recent years. What differentiates keto is that it’s extremely low in carbs, with just 5% to 10% of your energy intake coming from carbohydrate food sources. Lots of people assume keto is a high-protein diet, but it’s actually much higher in fat.

Is it healthy? While keto may offer some health benefits to certain demographics, the general answer: not exactly. “There’s not much research that backs the elimination of any single nutrient or food group in helping you keep off weight for the long-haul,” London says, adding that research has linked long-term adherence to the keto diet (for the treatment of pediatric seizure disorders) to long-term complications, including bone loss, organ-function abnormalities, micronutrient deficiencies, and gastrointestinal problems.

Adults interested following a keto plan for weight loss, beware: “Any time you have to nearly eliminate an entire food group from your diet, you eliminate all the various health benefits from some of nature’s most nutrient-dense foods,” London says, citing fruits and veggies, which are permitted only in limited quantities on the keto diet, plus whole grains, legumes, and dairy products. “These are a big part of a healthy pattern of eating,” she says.

What’s more, to replace the nutrients found in eliminated foods, people following keto often need dietary supplements. “When you rely on dietary supplements and animal foods on the keto diet, it gets expensive,” London says. And don’t forget potentially unpleasant side effects like “keto flu” and “keto breath.”


How to try it:

Since WW is backed by nutrition science, we’re not advocates for heavy-duty restrictions when it comes to weight loss. After all, carbohydrates (like whole grains, fruits, vegetables, and legumes) are the preferred source of energy to fuel the body. If you’d still like to try it, our program can help you discover more nutritious carbs and promote healthier eating habits overall. To start:

  • Choose unsaturated fats. Plant-based sources of polyunsaturated and monounsaturated fats from veggies, legumes, oils, nuts, seeds, avocado, and more are welcome—and encouraged.
  • Notice the types of carbs you’re eating. On WW, you can use your budget any way you’d like. But as you start tracking the foods you eat, take note: Are the carbohydrates you’re choosing refined (i.e., crackers, chips, or doughnuts) or whole grains and produce? “Choosing more nutrient-dense, unprocessed carbs regularly is part of a health-promoting pattern of eating,” London says.
  • Build meals around ZeroPoint foods. Seafood, low-carb vegetables, low-fat poultry, eggs, plain low-fat yoghurt, and berries are staples of the keto diet.

4. Intermittent fasting


What it is: Intermittent fasting is an approach to eating that requires you to partially or fully abstain from food and beverages for a given period of time, like only eating within an eight-hour window each day.

Is it healthy? “There’s not a strong or large body of evidence in humans on intermittent fasting for long-term health or weight management,” London says. That said, if timing meals and snacks helps you plan them more strategically or get to bed earlier (more on that below), this approach to eating could benefit you. “If you know you’ve only got a certain amount of time to eat, you may be more primed to plan ahead for those times in which you are eating, so that you don’t waste time or graze mindlessly,” London says, adding that tracking during the hours when you’re not fasting can help, too.


How to try it:

  • Plan ahead for meals and snacks. Prep some quick and easy items—apples and cheese, whole grain crackers and peanut butter, or defrosted batch-cooking—so that you have food ready to go during your non-fasting window. Reduced kilojoules during the day can lead to overeating at night, so having a meal plan in place is a smart move.
  • Go to sleep earlier. Getting to bed at a reasonable hour—a crucial component to weight loss, since getting seven hours of sleep per night as been linked to weight management, reduced risk of chronic disease, and improved metabolic benefits—can help you limit the amount of time you spend eating. So after your last meal, brush your teeth, shut down your computer, turn off your TV, put your phone on “do not disturb,” and say goodnight to late-night snacking!


5. Paleo diet


What it is: Paleo is a dietary plan where you eat foods that are similar to what might have been eaten during the Paleolithic era, which dates from approximately 2.5 million to 10,000 years ago.

A paleo eating plan typically consists of ingredients that would have been obtained by hunting, fishing, and gathering—that means lean meats, fish, fruits, vegetables, nuts, and seeds. A paleo diet limits foods that became common when farming emerged, so no dairy products, legumes, grains, refined sugar, salt, or highly processed foods are permitted.

Is it healthy? While the paleo diet could offer some health benefits for certain people, any time you eliminate an entire food group, you risk nutrient deficiencies and feeling deprived, which could lead to overeating and a reversal of any weight loss. Plus, “there’s no scientific rationale behind some of the arbitrary restrictions placed on various foods and among different types of paleo diets,” London says. Instead, opt for making conscious choices about the types of carbs you eat. London recommends plenty of fresh produce, whole grains, legumes and pulses, and low-fat plain dairy products, which help form the basis of a healthy eating pattern.

Following an approach to weight loss that restricts entire food groups is unlikely to be sustainable–and doesn’t help people develop and maintain long-term healthy habits.


How to try it:

  • Lean on your ZeroPoint foods. Many of these foods are compatible with paleo, including fruits and vegetables, and lean meats and fish.
  • Use your budget for foods that aren’t ZeroPoint but fall into the paleo eating approach. Nuts, seeds, and healthy oils and fats, which are permitted on the paleo diet, can easily fit into your Points Budget.