Diet Scoring System

Each diet we review is individually scored across five different domains on a 1-5 Likert scale (i.e., no half scores), and then a rounded median is calculated for the "overall" score for the diet. Individual domain scores are available at the bottom of each review article.

1. Health benefits of the diet
2. Nutrient content of the diet
3. Weight loss and weight control
4. Feasibility: How easy it is to follow.  
5. Safety profile and adverse events

We only score diets that are used or promoted for general use, regardless of their original (or intended) purpose. Specialist "therapeutic" diets that are designed solely to treat specific health conditions or medical needs are reviewed, but not scored under the rubric. 

Diets that have therapeutic use but have been widely adopted beyond their original clinical context are scored (e.g., ketogenic, very low-calorie, MIND, DASH and TLC diet). Their therapeutic effects are still discussed in the article, but this may not be reflected in the overall score.

Overall Score

• ★★★★★ = Overall, the evidence is strong, and the diet is highly recommended for general adoption; it consistently shows benefits across multiple outcomes and is broadly sustainable with minimal trade-offs.
• ★★★★☆ = Overall, the evidence is good and the diet is suitable for most people; the majority of dimensions are positive, with only minor trade-offs or caveats in one or two areas.
• ★★★☆☆ = Overall, the evidence is mixed, and the diet is recommended only with caution; it may be suitable for specific populations or short-term use, but is not broadly recommended without consideration of individual circumstances.
• ★★☆☆☆ = Overall, the diet offers limited benefits with notable drawbacks; practical and safety concerns limit its suitability for most people and it is not broadly recommended.
• ★☆☆☆☆ = Overall, the diet performs poorly across all dimensions assessed; the evidence consistently points to harm or serious sustainability failures and adoption should be actively discouraged without specialist medical oversight.

Health Benefits

• ★★★★★ = Strong, consistent health benefits across two or more major outcomes, supported by three or more independent meta-analyses or five or more high-quality randomised controlled trials showing reduced disease risk or mortality.
• ★★★★☆ = Clear health benefits across one or more major outcomes, supported by two or more high-quality randomised controlled trials or at least one meta-analysis with consistent results; minor inconsistencies may be present in a small number of studies.
• ★★★☆☆ = Evidence of benefit is limited to short-term outcomes or biomarker improvements, rather than clinically meaningful disease endpoints. Available studies are often small, short, or lack independent replication.
• ★★☆☆☆ = Evidence is inconsistent or low quality, with no reliable demonstration of reduced disease risk or improved health outcomes; findings are frequently contradictory or limited to poorly controlled research.
• ★☆☆☆☆ = There is credible evidence of harm or absence of meaningful benefit; the diet is associated with increased disease risk, adverse metabolic outcomes, or other measurable negative health effects.

Nutrition

• ★★★★★ = The diet meets over 90% of the recommended daily allowance for over 90% of essential nutrients, includes all major food groups, and requires no supplementation.
• ★★★★☆ = The diet meets over 80% of the recommended daily allowance for more than 80% of essential nutrients; therefore, no more than one supplement is likely needed to address minor gaps.
• ★★★☆☆ = The diet has moderate nutritional adequacy but shows gaps in one or two essential nutrients or excludes at least one major food group, which may require adjustment or supplementation over time.
• ★★☆☆☆ = The diet is likely to result in two or more nutrient deficiencies or requires exclusion of multiple major food groups, posing a meaningful risk of nutritional inadequacy.
• ★☆☆☆☆ = It involves severe nutritional restriction or promotes unsafe intake levels — such as very high sodium or saturated fat, or critically low carbohydrate or fibre — inconsistent with established nutritional safety thresholds.

Weight Control

• ★★★★★ = Multiple high-quality studies report measurable weight loss of over 5%, sustained beyond 12 months in overweight or obese participants. Those who follow the diet are very likely to maintain a healthy body weight over time.
• ★★★★☆ = Studies report moderate, sustained weight loss of around 5% over six to twelve months with reasonable adherence in overweight or obese people. Those who follow the diet are likely to maintain a healthy body weight over time.
• ★★★☆☆ = Short-term weight loss of over 3% has been observed in some studies, but maintenance beyond six months is poor and regain is common in overweight or obese people. Those who follow the diet may be able to maintain a healthy body weight over time.
• ★★☆☆☆ = Weight loss outcomes are minimal, trivial, or inconsistent across studies, with average losses of less than 3%; dropout rates are high, limiting the reliability of even short-term findings. Those who follow the diet are unlikely to maintain a healthy body weight over time.
• ★☆☆☆☆ = The diet is ineffective for achieving and maintaining a healthy body weight and is associated with weight cycling, significant regain beyond baseline, or short-term losses that are not sustained. Those who follow the diet are very unlikely to maintain a healthy body weight over time.

Ease to Follow

• ★★★★★ = The diet is accessible, flexible, low-cost, and socially adaptable, with studies reporting over 70% adherence beyond six months.
• ★★★★☆ = Adherence rates of 50–70% are reported; cost and planning demands are moderate.
• ★★★☆☆ = Adherence rates of 30–50% are reported; cost, social barriers, or dietary restrictiveness present meaningful challenges to long-term adoption.
• ★★☆☆☆ = Adherence rates are below 30%; the diet is often costly, complex, or socially limiting.
• ★☆☆☆☆ = Adherence rates are below 15%; the diet is frequently described as socially isolating, financially demanding, or incompatible with normal daily life.

Safety Profile

• ★★★★★ = It is safe for most people, broadly aligns with dietary guidelines, and has no adverse effects.
• ★★★★☆ = The diet is generally safe for healthy adults, with only minor reversible effects and no significant safety concerns.
• ★★★☆☆ = The diet is generally safe but may pose risks for certain populations, including people with diabetes, kidney disease, or other vulnerable populations with pre-existing conditions.
• ★★☆☆☆ = Documented adverse effects have been reported, nutritional deficiencies are common and well-evidenced, and medical supervision is recommended.
• ★☆☆☆☆ = It carries a high risk of harm, with documented links to measurable health damage, nutritional deficiency, or elevated risk of disordered eating.