A Cardiologist Reviews the Most Popular Weight-Loss Programs

Updated July 2026

There seem to be as many opinions about the "best" diet as there are diets. One day a food is good for us, the next day it is bad, and we lurch from headline to headline, buying bags of grapefruit one week and bags of cookies the next.

I have spent years watching patients cycle through these programs, so I want to walk through the most popular ones and tell you honestly what each gets right and where it falls short. My bias is simple, and I will say it up front: I care far more about whether a plan builds your long-term health than about how fast it drops a number on the scale. Almost every commercial program is built around the second goal and quietly ignores the first.

There is one more truth worth stating at the outset, because everything below rests on it. Weight loss happens only when a diet, or a weight-loss medication, leads you to take in fewer calories. That is the whole game, and there is no secret hiding underneath it. So what I am really examining with each of these programs is how it gets you to eat less, and what you give up in the process.

Do low-carb, high-protein diets like Atkins and Paleo actually work?

They can produce weight loss, but they are built on a premise I do not think holds up for long-term health. Both Atkins and Paleo center meals on animal protein and fat while cutting carbohydrates. When you keep carbohydrates low, insulin levels drop and your body burns more fat, and because high-protein meals curb appetite, most people eat fewer calories without counting them.

The problems show up when you look past the scale. Most of the short-term studies show people regain the weight within a year, usually because the plans are hard to sustain. More important to me as a cardiologist, very low-carb eating has been shown to impair the ability of your arteries to dilate and function normally, and healthy, flexible blood vessels are central to protecting you from heart attacks and strokes. Diets heavy in red and processed meat also carry their own risk, and processed meat in particular is classified as a definite carcinogen for colorectal cancer.

Paleo adds a layer of storytelling that does not match reality. The idea that early humans ate meat as a daily staple is romantic but wrong, since hunting large animals was dangerous and unreliable, and daily meat was not the mainstay the marketing suggests. Paleolithic humans may have been lean, but they were also highly physically active, and they lived, on average, to about 35.

Here is what tends to get lost in the low-carb enthusiasm. The essential micronutrients we need for good health, the vitamins, antioxidants, and fiber, can only be found as part of a carbohydrate package, which is likely why, in clear contrast to animal-based foods, eating fruits and vegetables reduces your cancer risk. You can also bring insulin down by choosing whole, unprocessed carbohydrates like oats, farro, and wheat berries instead of cutting carbs out. Fiber is every bit as filling as protein. And protein comes from plants as readily as from animals. The populations around the world with the longest healthy lifespans eat plenty of produce and whole grains alongside modest amounts of meat and fish, not in spite of the carbs but partly because of them.

One note, because I have written elsewhere about protein and muscle. None of this means protein is the enemy. Getting enough protein matters a great deal, especially for women and for anyone trying to hold onto muscle as they age. About 1.2 grams per kilogram of ideal body weight per day is plenty for most people, even those who are moderately active, which works out to roughly 0.5 grams per pound. The issue with Atkins and Paleo is not that they include protein, it is that they build the entire day around animal protein and treat carbohydrates as something to fear.

Do fad diets like the grapefruit, cabbage soup, or cookie diet work?

They can take weight off briefly, but only by cutting calories, and none of them lasts. The grapefruit diet, the cabbage soup diet, the banana diet, and the rest of the single-food plans all run on the same trick. When you build your meals around one low-calorie food and little else, you get bored, you eat less, and the scale moves for a week or two. The Cookie Diet is almost a parody of the idea: eat six branded cookies through the day, then have one regular dinner, which lands you around 1,000 to 1,200 calories.

But all of these are built on restriction alone, with no attention to what is actually in the food or whether you could ever keep it up. With the Cookie Diet, you would get roughly the same calories, protein, and fiber from a couple of grocery-store cookies, at a fraction of the cost. Eating the same food day after day is monotonous enough that most people quit. If a plan sounds too good to be true, it usually is.

How healthy are meal-delivery programs like Nutrisystem?

Meal-delivery programs solve the convenience problem, but most of them, Nutrisystem included, solve it with heavily processed food. The structure is portion control through ready-to-eat meals at around 1,200 to 1,500 calories a day, with decent fiber and controlled sodium, which sounds reasonable on paper.

The trouble is in the details. The menus lean on items like pizza and mac and cheese, and the foods are built with the additives, artificial flavors, and preservatives that come with shelf-stable convenience. Because you are eating these products from morning to night, that matters more here than it would for an occasional meal. The programs also do not teach you how to eat once you finish, so maintaining any loss is difficult, and they typically require you to eat their food exclusively, which means no family dinners or meals out for the length of the plan. For someone with a lot of weight to lose, that can mean nearly a year of eating only packaged food, at a cost of several hundred dollars a month on top of the produce and dairy you still have to buy.

When we designed Step One Foods, we studied programs like this one closely. We kept the parts that work, the pre-portioned, easy-to-prepare structure, and rejected the parts that do not, the reliance on processed ingredients and the way the program owns your stomach from morning to night. More on that below.

Does Weight Watchers help you eat healthier?

Weight Watchers, now WW, gets more right than most, but its food guidance has a real blind spot. Rather than selling you its own meals, it assigns points to real-world foods and lets you eat what you like within a daily total. The flexibility is genuinely useful, fruits and most vegetables score zero, and the broader program includes fitness and social support that help people stick with it.

The blind spot is that the points math treats all foods of similar macronutrient content as equivalent, regardless of what is actually in them. You can spend your points on ultra-processed snacks and stay perfectly "on plan" while eating poorly. The calculator cannot read an ingredient panel, so it scores all fiber the same whether it comes from added inulin or from whole food. That means a small cookie with added fiber can be assigned fewer points than an apple or a bowl of oatmeal. In addition, ingredients that may undermine your health, like dyes and artificial sweeteners, pass right through the system unflagged.

I will say that WW has changed considerably over the years and now wraps in coaching and even medical weight-loss services, so the program is a moving target. But the core lesson stands. A points or calorie system is a fine tool for losing weight and a poor teacher of how to eat well. If you use WW, plan to learn how to read ingredient lists on your own, because the points alone can lead you astray.

What about high-protein meal-replacement plans like Optavia?

Optavia, a subsidiary of Medifast, earns points for structure and vegetables but pushes protein and processing further than I can endorse. The plan has you eat several fortified Optavia products a day plus two "Lean and Green" meals you make yourself. I like that it gets people cooking a bit and asks for six servings of vegetables a day. Any plan that pushes vegetables that hard has my attention.

Two things stop me from recommending it. First, the protein load is high enough that a typical day can stack well past what most non-athletes need, and building every day around that much protein and that little carbohydrate is essentially Atkins in a different package. Second, the products are so heavily fortified that they read more like supplements than food. This should not be overlooked. The published evidence is consistent that whole foods are a better source of nutrients than fortified formulations, because the nutrients arrive in a form your body recognizes and uses. Getting your vitamin C from berries or an orange beats getting it from a fortified bar any day.

Is Seattle Sutton a good option?

Seattle Sutton is better than most meal-delivery plans on freshness, but its lack of transparency and its lack of an exit are real drawbacks. As part of its full plan, it delivers 21 freshly prepared meals a week on rotating menus, which helps with monotony.

What gives me pause is that this was the only food company I have reviewed that did not publish full ingredient information before purchase. I had to call and request labels, and even then received only a partial set. Every dish I did see contained added sugar. You cannot choose your meals within a plan, so a dish you disliked simply comes back around, and the cost runs to roughly $600 a month, among the highest I have seen. Most important, like the other delivery plans, it gives you no off-ramp and no food skills, and that missing exit is precisely why most of these programs eventually fail.

Where do GLP-1 medications like Ozempic and Wegovy fit in?

GLP-1 medications reduce appetite, slow digestion, and modulate blood sugar fluctuations. All of these effects lower the desire to eat, which can lead to a markedly reduced calorie intake. And indeed, these drugs can produce weight loss that no commercial diet program has matched. But because they work largely by reducing how much you eat, the quality of the food you do eat matters more than ever, not less. Rapid weight loss also costs you muscle unless you are deliberately protecting it with adequate protein and resistance training. In other words, these medications are not complete or stand-alone solutions. They must be surrounded by strategic, comprehensive lifestyle changes.

So what actually works for weight loss?

As I reflect on all of these programs, what strikes me is how HARD they are. Counting points, avoiding carbs, deprivation, starvation, injecting yourself with drugs. None of it seems sustainable, or pleasurable.

So here is my advice. Stop thinking about losing weight and start thinking about building health.

What I have seen in my own practice is that the approach that holds up is not a brand. It is a philosophy, and the writer Michael Pollan summed it up in seven words: "Eat food. Not too much. Mostly plants."

That means eating food made from real ingredients in their most whole and natural form, the kind your great-grandmother would recognize as food. Fill your plate with fruits and vegetables, whole unprocessed grains, beans and legumes, nuts and seeds, and modest amounts of lean protein. And don't stuff yourself. Do that consistently and you will feel better, your numbers will improve, and the weight will take care of itself. No points, no drugs, no deprivation, no starvation.

That principle is the entire reason Step One Foods exists. We built our clinically validated program around whole-food ingredients that deliver meaningful doses of the nutrients shown to improve cardiovascular health. It is two simple servings a day, designed to fit into real life. And people who start using our foods to lower their cholesterol often find their weight improves too. Turns out, the best eating plan is the one you can actually keep.

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