Popular Diets Explained

If you’ve ever tried to lose weight or eat healthier, you’re not alone. In fact, most adults in the western world are actively trying to manage their weight. But despite all the effort, the numbers tell a different story: in England, around 64.5% of adults are overweight or living with obesity, with more than a quarter falling into the “obese” category.

Why does this matter? Carrying excess weight is linked with higher risks of heart disease, type 2 diabetes, high blood pressure, stroke, joint problems, sleep issues, and even some cancers. Understandably, this motivates people to look for solutions — but sticking to lifestyle changes is often harder than starting them. Research shows that people’s main reasons for wanting to lose weight aren’t always medical — more often, it’s about how they feel in their own skin and day-to-day comfort.

Type “diet books” into Amazon and you’ll be flooded with thousands of results: low-carb, intermittent fasting, detox cleanses, and everything in between. But what’s the real deal? Are these diets backed by science? Do they actually help with fat loss (rather than just water or muscle)? Do they improve health markers like cholesterol, blood pressure, and blood sugar? And are they sustainable — or just another short-term fix?

Before we dive into the diets, here’s the bottom line: weight change comes down to energy balance.

• If you take in more calories than you burn, you gain weight.

• If you burn more than you consume, you lose weight.

• If the two balance out, your weight stays the same.

Sounds simple, right? But in reality, appetite, habits, emotions, and lifestyle make it much more complicated. That’s why so many different diets exist — each one offers a different approach to controlling energy balance and supporting health.

 Now, let’s take a closer look at some of the most well-known diets, what they involve, and their pros and cons.

 Atkins Diet (Low-Carb, Similar to Keto)

The Atkins Diet is one of the original low-carbohydrate approaches, created by Dr. Robert Atkins in the 1970s. It emphasises protein and fat while sharply restricting carbohydrates, especially in the early phases. The goal is to push the body into ketosis, a state where fat is burned for energy instead of glucose, before gradually reintroducing carbs as weight goals are achieved.

One of the main advantages of Atkins is that it can lead to rapid weight loss in the short term, often because people eat fewer calories without consciously restricting portions. Many find their blood sugar stabilises, cravings are reduced, and hunger is less of a problem when carbs are kept low. Studies have also shown improvements in triglycerides and HDL cholesterol, and for some people with type 2 diabetes, Atkins-style eating can help manage glucose levels.

However, the disadvantages are significant. The diet can be highly restrictive, cutting out fruits, whole grains, and many vegetables, which makes it difficult to meet daily fibre, vitamin, and mineral needs. For those who rely heavily on fatty meats and cheeses, there is also a risk of consuming too much saturated fat, which may increase cardiovascular risk. Most importantly, adherence tends to be poor over the long term, with many people regaining lost weight once they return to old habits.

DASH Diet (Dietary Approaches to Stop Hypertension)

The DASH diet was designed by researchers in the 1990s to help reduce high blood pressure, and it remains one of the most recommended eating patterns by health professionals. It focuses on fruits, vegetables, wholegrains, lean protein, nuts, and low-fat dairy, while limiting salt, red meat, sugar, and saturated fats.

Its main advantage is that it is evidence-based and clinically proven. Research consistently shows that DASH lowers blood pressure, improves cholesterol levels, and reduces the risk of heart disease, stroke, and type 2 diabetes. It is balanced, nutrient-rich, and flexible enough to adapt to personal preferences, making it sustainable for the long term.

The downsides are relatively minor, but worth noting. For people used to a high-salt or highly processed diet, reducing sodium can be challenging and sometimes discouraging at first. The higher fibre intake can cause digestive discomfort initially, and weight loss with DASH tends to be modest unless calories are also consciously reduced. That said, compared to more restrictive diets, its disadvantages are fewer and easier to manage. 

Glycaemic Index (GI) Diet

The Glycaemic Index diet is built around the concept of choosing carbohydrates that have a lower impact on blood sugar. Foods are ranked according to how quickly they raise blood glucose, with low-GI options like beans, oats, and non-starchy vegetables encouraged, and high-GI foods like white bread, sugary snacks, and potatoes discouraged.

The main advantage of the GI diet is that it can improve blood sugar control, making it especially helpful for people with diabetes or insulin resistance. By favouring slow-release carbohydrates, it may also help with appetite regulation and reduce energy crashes, which in turn can support weight management.

On the other hand, the GI system is not always practical. It does not account for portion sizes or the overall nutritional value of foods. For example, chocolate has a lower GI than watermelon, which makes the ranking confusing in real-world settings. The complexity of calculating and monitoring GI values can make the diet hard to follow, and without attention to overall balance, it may not provide complete nutrition.

Mediterranean Diet

The Mediterranean diet is inspired by traditional eating patterns in countries like Greece and Italy. It emphasises plant-based foods such as vegetables, fruit, legumes, nuts, and wholegrains, along with olive oil as the main fat source. Fish and seafood are eaten regularly, poultry and dairy in moderation, and red meat and sweets only occasionally.

The great strength of this diet is its proven health benefits. It is one of the most extensively studied eating patterns and has been linked with reduced risk of cardiovascular disease, type 2 diabetes, some cancers, and improved cognitive health. It is nutrient-dense, balanced, and varied, making it enjoyable and sustainable for most people.

The drawbacks are relatively few but worth mentioning. It is not specifically designed for rapid weight loss, so those seeking quick results may be disappointed. The focus on fresh produce, fish, and olive oil can also make it more expensive than a typical Western diet. For people who prefer convenience foods or dislike cooking, it may require more planning and preparation.

Palaeolithic (Paleo) Diet

The Paleo diet is based on the idea of eating like our hunter-gatherer ancestors, which means plenty of meat, fish, vegetables, nuts, and fruit, while cutting out dairy, grains, legumes, and processed foods. The philosophy is that modern diseases stem from a mismatch between our current diets and the foods our bodies evolved to eat.

Supporters of the Paleo diet often see benefits such as weight loss, better blood sugar control, and improved satiety, largely because it eliminates highly processed foods and emphasises protein and fibre-rich choices. It encourages whole, minimally processed foods and reduces added sugars, which is positive from a health perspective.

But the diet also comes with significant downsides. By excluding entire food groups like wholegrains and legumes, it risks missing out on important nutrients, particularly calcium and fibre. It can be expensive due to the focus on high-quality meats and fresh produce, and socially restrictive because many everyday foods are off-limits. Furthermore, the “ancestral” justification is debated, since Paleolithic diets varied widely across regions and seasons.

Ornish Diet

Developed by Dr. Dean Ornish, the Ornish diet is a very low-fat, predominantly plant-based approach. Less than 10% of daily calories come from fat, with an emphasis on fruit, vegetables, whole grains, legumes, soy, and non-fat dairy. Alongside the dietary component, the Ornish program often includes lifestyle interventions such as exercise, stress management, and social support.

The standout advantage of this diet is that it is the only one shown in clinical studies to actually reverse heart disease when combined with lifestyle changes. It is high in fibre and low in calories, which naturally supports weight loss. It is also rich in vitamins, minerals, and antioxidants, offering broad protective effects against chronic disease.

The main disadvantage is its extreme restrictiveness. By excluding nearly all fats, including healthy ones like nuts, seeds, and avocado, it can feel unsatisfying and difficult to sustain. The risk of deficiencies in omega-3 fatty acids and vitamin B12 is also a concern without supplementation. Many find the strict rules socially isolating and challenging for the long term.

Zone Diet

The Zone diet, popularised by Dr. Barry Sears, is structured around eating meals with a 40:30:30 ratio of carbohydrates, protein, and fat. It also promotes small, frequent meals throughout the day to maintain hormonal balance and control insulin levels.

The advantage of the Zone diet is that it promotes balance and portion control. Some people find the structure helpful for avoiding overeating, and the emphasis on moderate protein and reduced refined carbohydrates can improve satiety and help with blood sugar regulation.

However, the evidence supporting the Zone diet is limited, and its practical demands make it difficult to follow. Measuring and balancing macronutrient ratios at every meal requires meticulous planning, and eating frequent small meals can feel restrictive in daily life. The diet can also be low in fibre and micronutrients if not carefully managed, leading to potential nutritional gaps.

Important Considerations when Choosing Any Diet

When evaluating any diet, there are key factors beyond the promises of weight loss or health improvement. In terms of body composition, many diets can lead to rapid initial changes, but much of this is water rather than fat, and without resistance training, lean muscle can be lost alongside fat. Nutritional adequacy is another concern: restrictive diets often cut out entire food groups, which can result in deficiencies unless carefully planned. This is especially important if you have pre-existing medical conditions.

Metabolic parameters such as blood glucose, cholesterol, and blood pressure are often improved in the short term, particularly when weight is lost, but long-term effects can vary and are highly individual. For instance, some people may see LDL cholesterol rise on high-fat, low-carb diets. Finally, hunger and compliance are crucial. A diet that leaves you constantly hungry, socially restricted, or requires too much effort is unlikely to be maintained, leading to weight regain and frustration.

And finally….

Every diet has its champions and critics, but the truth is that no single approach works for everyone. The best diet is one that provides adequate nutrition, supports a healthy body composition, improves key health markers, and, most importantly, can be sustained in the context of real life. Extreme diets may deliver fast results but often fail the test of long-term adherence, while more balanced approaches like DASH or the Mediterranean diet offer steady, lasting benefits.

At the end of the day, the “best” diet is not the one that sounds the most exciting or promises the fastest results — it’s the one you can live with, enjoy, and maintain as part of a healthier lifestyle.

References

1. Atkins Diet – Short-Term Weight Loss
   Dansinger, M. A Randomized Trial of a Low-Carbohydrate Diet for Obesity, New England Journal of Medicine. This trial outlines the four phases of Atkins and demonstrates initial weight-loss patterns tied to carbohydrate intake.

2. Atkins Diet – Long-Term Efficacy
   Johnston, B. C., et al. Long-Term Effects of 4 Popular Diets on Weight Loss and Cardiovascular Risk Factors, Circulation: Cardiovascular Quality and Outcomes. This meta-analysis found modest, short-term benefits for Atkins, which diminish over time, making its long-term advantage questionable.

3. DASH Diet – Blood Pressure Impact
   Appel, L. J., et al. A Clinical Trial of the Effects of Dietary Patterns on Blood Pressure, New England Journal of Medicine. The original DASH trial demonstrated that a healthy eating pattern significantly lowers blood pressure in adults.

4. Mediterranean Diet – Cardiovascular Outcomes (PREDIMED)
   Estruch, R., et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet, New England Journal of Medicine. This landmark study showed that a Mediterranean diet supplemented with olive oil or nuts cuts cardiovascular events by about 30%.

5. Mediterranean Diet – Cohort & Mortality Data
   Aleksandro Tognon, et al. Prospective Association of the Mediterranean Diet with Cardiovascular Disease Incidence and Mortality, BMC Medicine. In a large cohort with ~12 years of follow-up, higher adherence to a Mediterranean-style diet significantly reduced CVD risk and all-cause mortality.

6. Ornish Diet – Heart Disease Reversal Trial
   Ornish, D., et al. Intensive Lifestyle Changes for Reversal of Coronary Heart Disease, JAMA. In this highly influential trial, comprehensive lifestyle changes—including a very low-fat diet, stress management, and exercise—led to regression of atherosclerosis.