Beyond Fad Diets: What A Doctor Recommends

Every week, there’s a new diet trend claiming to be the solution to lasting weight loss. Juice cleanses, fasting challenges, no carb regimens—these plans might promise rapid results, but often, the weight returns.

As a physician specializing in obesity medicine, here's what I know for certain: There are only two dietary approaches that consistently produce real, sustainable results. And they’re not trendy hacks or crash diets. They’re both “ad libitum” (eat to fullness) diets that aren’t calorie restricted, making them successful weight loss strategies rooted in decades of research and real-world success. Let’s explore them.

The first approach is a high-fat diet, like the ketogenic and Atkins plans. The science behind it is fascinating: By drastically reducing carbohydrate intake and increasing fats, you force your body into a state called ketosis.

In ketosis, your body stops relying on glucose from carbs for energy and starts burning fat instead. This metabolic shift not only promotes fat loss but can also stabilize blood sugar levels and reduce hunger.

People often describe their experience on keto as transformative. They feel less hungry, more energetic, and see meaningful weight loss, sometimes quickly. Foods in this diet include:

• Proteins and fats: Fatty fish, eggs, avocados, nuts, seeds, and oils (like olive or coconut).
• Low-carb vegetables: Spinach, kale, broccoli, and cauliflower.
• Minimal carbs: Restricting carbs to as little as 20 to 50 grams per day is key, which means foods like bread, pasta, and sugary snacks are off-limits.

Keto diet risks: While this diet can be effective, it’s also strict and can be difficult to maintain. Social situations, cravings, and the monotony of high-fat foods can lead to burnout. There’s also a risk of nutrient deficiencies, particularly in fiber, as fruits, beans, and whole grains are typically avoided.

Constipation is another common side effect, as are “keto flu” symptoms like fatigue and irritability when starting out. If you’re considering keto, it’s wise to consult a health care provider to ensure you’re meeting all your nutritional needs.

On the other end of the spectrum is the high-fiber, whole foods diet. This approach focuses on minimally processed, nutrient-dense foods that fill you up while keeping calories in check. Fiber is the star here—it slows digestion, stabilizes blood sugar, and keeps you feeling satisfied.

One of the reasons this plan works so well is that fiber-packed foods are naturally low in calories and high in volume, which means you can eat satisfying portions without overindulging. It’s also more flexible than keto—you can incorporate a wider variety of foods and flavors, making it easier to sustain over the long term.

This diet is about abundance, not restriction. Foods in this plan include:

• Legumes and pulses: Lentils, black beans, chickpeas, and split peas.
• Whole grains: Brown rice, quinoa, whole-grain bread, and pasta.
• Fruits and vegetables: Apples, berries, leafy greens, sweet potatoes, and more.
• Healthy starches: Potatoes, yams, and squash.

High-fiber diet risks: This approach requires a commitment to cooking. If you’re used to prepackaged meals, whole, minimally processed foods can be difficult to prepare at first. Additionally, some people struggle with bloating or gastrointestinal discomfort when they increase their fiber intake too quickly, so gradual changes are key.

Both diets share one critical feature: An emphasis on whole, unprocessed foods. That’s where the magic happens. Ultra-processed foods—those high in refined carbs, unhealthy fats, and artificial additives—disrupt hunger signals and make it nearly impossible to manage weight effectively. Without them, sustainable weight loss is infinitely easier.

But no diet is perfect. High-fat diets can lack fiber and lead to digestive issues, while high-fiber diets might fall short on protein or healthy fats if not carefully planned. The key to success lies in understanding your body’s needs and making adjustments along the way.

For many of my patients, the idea of diving headfirst into a new diet feels overwhelming. That’s normal. The best way to start is with small, manageable changes. If you’re considering keto, experiment with reducing your carb intake gradually. If a high-fiber diet appeals to you, start by adding beans or whole grains to your meals a few times a week.

And there’s no universal timeline for success. Some people see results quickly, while for others, it takes months. What matters most is finding a plan that feels sustainable and allows you to live your life fully.

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