Every plan on this site is scored against the same six criteria, using the same definitions, and the overall rating is calculated rather than assigned. This page sets out exactly how that works — including where the method has limits.
The six criteria
Each is scored from 0 to 5 in half-point steps. The overall rating is their weighted average.
| Criterion | Weight | What it measures |
|---|---|---|
| Safety & evidence | 25% | Clinical support, documented risks, medical suitability |
| Nutrition quality | 20% | Macronutrient balance, food variety, micronutrient coverage |
| Sustainability | 20% | Long-term adherence, lifestyle fit, flexibility |
| Results | 15% | Short- and long-term outcomes |
| Cost & value | 10% | Total cost of following the plan, food included |
| User experience | 10% | Clarity of the rules and the daily burden of following them |
Safety, nutrition and sustainability carry 65% between them. That is deliberate. This site exists to help you find a plan that fits your life for the long run — not the one that strips the most weight fastest.
Two rules we hold ourselves to
Scoring diets that have no company behind them
Plenty of diets are not products. They are a book, an eating pattern, or a set of rules circulating online, with nobody selling anything. We score those on the same six criteria, with three clarifications.
Safety & evidence 25%
Clinical support for the approach, documented risks, and suitability across different groups of people.
| Score | What it means |
|---|---|
| 5 | Multiple randomised controlled trials or strong clinical consensus support the approach. No notable population-level cautions. |
| 4 | Reasonable trial support. Minor cautions for specific groups, such as pregnancy or particular medications, which the programme itself flags. |
| 3 | Limited or mixed evidence. Mainstream and widely used, but under-studied, or the trials are small, short, or industry-funded. |
| 2 | Thin evidence base, or documented cautions for identifiable groups — kidney impairment, a history of disordered eating, diabetes medication interactions — that are not adequately flagged by the plan’s primary source. Where there is no vendor to issue warnings, the absence of any contraindication guidance counts here rather than being set aside. |
| 1 | Contradicted by evidence, or carries meaningful risk of harm to a general audience. |
Peer-reviewed trials of the specific programme, not just its underlying eating pattern; the programme’s own stated contraindications; any warnings issued by regulators or professional bodies; and whether medical supervision is really required but not clearly stated. Where no vendor exists to publish contraindications, we treat that silence as a negative — a restrictive diet nobody warns anyone about is more dangerous, not less.
Nutrition quality 20%
Macronutrient balance, food variety, and micronutrient coverage across all phases.
| Score | What it means |
|---|---|
| 5 | Meets established macronutrient ranges throughout. Broad variety across all food groups. No predictable micronutrient gaps, and no supplements required. |
| 4 | Broadly balanced. One food group restricted, or one macronutrient consistently at the edge of recommended ranges. Supplements optional rather than necessary. |
| 3 | Adequate but narrowed — limited variety, heavy reliance on packaged or branded products, or one macronutrient persistently low. Nothing dangerous, but not what you would design from scratch. |
| 2 | Imbalanced in at least one phase. Predictable micronutrient shortfalls. Supplements effectively required to avoid deficiency, whether or not the programme says so. |
| 1 | Severely imbalanced. Eliminates entire food groups without replacement, or sustains macronutrient ratios well outside recommended ranges for extended periods. |
A sample week’s menu at each phase; fibre and micronutrient coverage, not just macros; whether required products displace whole foods; and whether the programme sells supplements to patch gaps it created.
Sustainability 20%
Whether a person can realistically stay on this indefinitely — and what happens when they stop.
| Score | What it means |
|---|---|
| 5 | Designed for indefinite use. Adapts to eating out, travel, family meals and cultural food preferences. No phase you have to come off. |
| 4 | Workable long-term with modest planning. The maintenance phase is genuinely livable and clearly defined. Occasional social friction. |
| 3 | Sustainable for months rather than years. Requires ongoing effort, expense or subscription to maintain. Most people will drift off it. |
| 2 | Built around a finite programme with a defined end. High relapse risk once it stops. Socially restrictive enough to complicate eating with others. |
| 1 | Cannot be maintained. Explicitly short-term with no maintenance path, or published follow-up shows adherence collapsing within months. |
Whether a maintenance phase exists and is specified in real detail; what it costs to continue indefinitely; published adherence and dropout rates; and how the plan handles a restaurant meal, a holiday, or a family dinner.
Results 15%
Weight and health outcomes, weighted toward what lasts.
Which outcome we score. A programme marketed for weight loss is scored on the weight anchors, whether or not it also improves health markers. An eating pattern that does not present itself as a weight-loss programme is scored on the health anchors. Every review states which set was used. Where a programme markets weight loss at all, the weight anchors govern — a plan does not get to be judged on health outcomes because its weight results are unimpressive.
Weight outcomes
| Score | What it means |
|---|---|
| 5 | Consistent, clinically meaningful loss in trials, with results substantially maintained at 12 months or beyond. |
| 4 | Reliable short-term loss, with reasonable evidence of retention at six to twelve months. |
| 3 | Loss comparable to any equivalent calorie deficit. Little or no long-term follow-up published. |
| 2 | Rapid initial loss with poor retention. Early results substantially water and glycogen rather than fat. |
| 1 | No credible evidence of results, or documented regain meeting or exceeding the loss achieved. |
Health outcomes
| Score | What it means |
|---|---|
| 5 | Consistent, clinically meaningful improvement in hard endpoints — cardiovascular events, mortality, diabetes incidence — in randomised trials, sustained at 12 months or beyond. |
| 4 | Reliable improvement in validated intermediate markers such as blood pressure, blood lipids or glycaemic control, with reasonable evidence of retention at six to twelve months. |
| 3 | Improvement comparable to any equivalent improvement in overall diet quality. Little or no long-term follow-up published. |
| 2 | Short-lived marker improvement with poor retention, or benefit confined to a single marker. |
| 1 | No credible evidence of health benefit, or documented worsening of measured endpoints. |
Which outcome the programme presents as its purpose, and whether its own marketing claims weight loss; the longest published follow-up available; whether trial comparison groups were matched for calories; whether reported results come from the company’s own marketing; whether average results count only the people who finished, which systematically flatters the number; and whether the people studied were taking weight-loss medication, which is handled under Medication and what we score.
A plan can score well here and still rate poorly overall. Fast weight loss achieved through means that are unsafe or unsustainable is captured by those criteria — it is not excused by this one.
Cost & value 10%
The total cost of actually following the plan — fees, required products and food — measured against what you would spend on food anyway.
Most diets are scored on their sticker price. We think that misleads in both directions. A meal-delivery plan looks expensive until you notice it is replacing your groceries. A free eating pattern looks cheap until you notice it runs on lean protein and fresh produce. What matters to your bank balance is the net additional cost: what you spend to follow the plan, minus what you were already spending to eat.
Our reference point is the USDA moderate-cost food plan, which puts a single adult at roughly $350–$400 a month in 2026. Bands below are net monthly figures above that baseline, and are reviewed every January.
| Score | What it means |
|---|---|
| 5 | Adds almost nothing — under roughly $25 a month net. No required purchases, and the food rules do not push your grocery bill up. |
| 4 | Adds roughly $25–$75 a month net. A modest subscription, a slightly pricier shop, or required products that are cheap or substitutable. |
| 3 | Adds roughly $75–$175 a month net. A real ongoing cost — a mid-priced subscription, noticeably more expensive groceries, or moderate required purchases. |
| 2 | Adds roughly $175–$350 a month net. An expensive subscription, mandatory branded food with no substitution, or food rules that substantially inflate the shop. |
| 1 | Adds more than roughly $350 a month net, or uses lock-in contracts, auto-ship arrangements, or cancellation processes that are difficult to exit. |
We adjust down one band for auto-renewal that is hard to cancel, aggressive upselling, exit fees, or headline pricing that requires a long prepaid term. There is no longer an upward adjustment for meal delivery — displaced groceries are now subtracted directly, which is more honest than a correction applied afterwards.
The true ongoing monthly cost after introductory offers expire; how much of your normal food spend the plan genuinely replaces, rather than assuming all or none; whether the plan’s own food rules raise the grocery bill, and by roughly how much; whether required products can be substituted; and the actual cancellation process, not the advertised one.
Until July 2026 this criterion scored programme price alone. That worked for meal-delivery services, where the price is the food, but it flattered food-pattern diets: a plan could score full marks for being free while quietly requiring an expensive shop. Scoring net cost fixes that. Two ratings moved as a result — see the change log at the foot of this page.
User experience 10%
Whether a person can follow the plan correctly, day after day — clarity of the rules, quality of the guidance, and the burden it places on ordinary life.
Tools are evidence, not the criterion. A polished app that leaves ordinary questions unanswered scores below a well-written book that answers them. Where an app exists we test it on a current device; where none exists, we score the primary written guidance on the same terms.
| Score | What it means |
|---|---|
| 5 | Rules are unambiguous and cover the situations real life actually produces. Minimal daily burden — little weighing, logging or special preparation. A beginner could follow it correctly from the first day. |
| 4 | Clear, well-organised guidance in whatever form it takes. Moderate preparation or planning. Occasional friction, but nothing that derails adherence. |
| 3 | Followable but effortful. Rules need interpretation in ordinary situations, or the daily burden is substantial — daily weighing, extensive logging, or significant cooking every day. |
| 2 | Guidance is confusing, contradictory, or scattered across sources. Heavy tracking demands, or rules a beginner would routinely get wrong. |
| 1 | No usable guidance, or rules that cannot be applied consistently. Onerous daily demands, opaque requirements, or commercial pressure that gets in the way of following the plan. |
Whether the guidance answers ordinary questions like what to eat at a wedding; how much time per day the plan realistically consumes; whether a beginner could follow it without prior nutrition knowledge; the app on a current device where one exists; and whether support is a real service or a sales channel.
The safety floor
If a plan scores 2.0 or below on Safety & evidence, its overall rating is capped at 3.0 and a caution appears on its card and review page. This deliberately overrides the weighted average. Without it, a plan could average its way to a recommendation on being cheap and easy while scoring poorly on safety — and that is not a rating we are willing to publish. The cap is applied automatically and cannot be waived for an individual plan. When it applies, we say so plainly in the review.
Medication and what we score
We rate diet plans. Our six criteria assess food, eating patterns and behaviour change — not prescription drugs, which we are not qualified to evaluate.
Programmes increasingly bundle prescription weight-loss medication alongside conventional plans. Rather than score around that, we state the boundary.
Drug-free plans are scored on their own merits
Where a programme offers several tiers, we assess each tier on what it actually requires. A plan that works through food is judged as a plan that works through food. The existence of a medication tier elsewhere in a company’s catalogue does not count against a plan that does not require it. No deduction, no asterisk.
Plans that require medication are not scored
A tier that requires prescription medication to be followed as designed falls outside what this method measures, and we do not rate it. The test is the programme’s own materials: if following the tier as the company describes it entails a prescription, it is out of scope.
An earlier version of this method scored such tiers and counted the requirement against them. That position could not hold. This section opens by saying we are not qualified to assess prescription medication; it cannot then publish a number that a medication requirement substantially determines. Either the method measures the thing or it does not.
Scoring the food component alone fails for a different reason. It would rate a programme nobody buys for its food component, and publish that rating alongside plans where the food is the programme. The half-point tolerance this method is built around assumes two reviewers are scoring the same object. Here they would not be.
Out of scope is not a verdict. It says this method is the wrong instrument, not that the programme is a poor one. Where a plan we cover has a medication tier alongside it, we describe that tier in the review so you know what it is. We simply do not give it a rating.
Companion programmes for people already on medication
Some programmes offer nutrition and behaviour coaching aimed at people already prescribed a GLP-1 medication by their own clinician. These supply no prescription and require none. They are food programmes, and we rate them.
They carry one restriction. Where the outcomes evidence for such a programme is drawn from people taking medication, it cannot on its own support a Results score above 3 — the anchor for loss comparable to any equivalent calorie deficit. A higher score needs evidence from people not on medication. Without that limit we would be crediting a drug’s results to a food programme, which is precisely what this section exists to prevent.
Where a company offers medication, we say so
Any review of a company offering medication tiers states this plainly, whether or not the reviewed plan uses them, and carries our standing position:
RatingDietPlans rates diet plans. Where a programme offers prescription weight-loss medication, we note it, and we do not regard it as a point in the programme’s favour. This is our editorial position, not a clinical judgement — we are not qualified to make one — and it is kept out of our scores. It is not advice about your own medication. If you have been prescribed a weight-loss medication, decisions about starting, continuing or stopping it belong with your prescribing clinician and nobody else.
The scope rule above follows from what this method can and cannot measure. The position in the box is editorial, and is labelled as such wherever it appears. We keep the two visibly separate so you can accept the scope rule and reject the position, or the reverse.
How this looks in practice
Every plan scored so far, with all six sub-scores shown.
| Plan | Safety | Nutrition | Sustain. | Results | Cost | UX | Overall |
|---|---|---|---|---|---|---|---|
| Mediterranean Diet | 4.5 | 4.5 | 5.0 | 4.5 | 4.0 | 3.5 | 4.5 |
| Jillian Michaels “The Fitness App” | 4.0 | 4.0 | 4.5 | 3.5 | 4.5 | 4.0 | 4.1 |
| WeightWatchers | 4.0 | 4.0 | 3.5 | 4.0 | 3.5 | 4.0 | 3.9 |
| South Beach Diet | 4.0 | 3.5 | 3.5 | 3.0 | 3.0 | 3.5 | 3.5 |
| Nutrisystem | 4.0 | 3.0 | 2.5 | 4.0 | 2.0 | 4.5 | 3.4 |
| Dukan Diet caution | 1.5 | 1.5 | 1.5 | 3.5 | 3.0 | 2.0 | 2.0 |
Worked example: the Dukan Diet
Safety 1.5 reflects documented kidney cautions and unsuitability for anyone with a history of disordered eating, inadequately flagged by the programme. Nutrition 1.5 reflects the near-elimination of both carbohydrates and fat in the attack phase. Sustainability 1.5 reflects a rigid four-phase structure with high documented relapse. Results 3.5 acknowledges real early weight loss, much of it water. Cost 3.0 — the programme itself is free, but its reliance on lean protein raises the grocery bill by roughly $75–150 a month, and that net figure is what the band reflects. User experience 2.0 for rigid rules and heavy self-monitoring.
Because Safety scored below 2.0, the safety floor engages and the caution flag is set. The 3.0 cap does not bind here, since 2.0 already sits below it.
Keeping scores current
Every review carries a last verified date. We re-verify each plan at least annually, and immediately whenever a programme changes its phases, pricing structure or required products, or when significant new trial evidence is published. Cost bands are reviewed each January against prevailing prices.
Re-verifying means re-checking the source material, not simply reconfirming the previous number. What changed gets recorded in the review itself, so you can see a score has been maintained rather than left to age.
Changes to this method
The weights change rarely, and never in order to produce a preferred outcome for a particular plan. When they do change, the date, the old and new values, and the reasoning are recorded here, and affected scores are re-verified before publication.
| Date | Change | Reasoning |
|---|---|---|
| July 2026 | Initial weights set | Safety 25 / Nutrition 20 / Sustainability 20 / Results 15 / Cost 10 / UX 10, reflecting a focus on long-term fit over short-term loss |
| July 2026 | Cost & value redefined as total cost of following the plan | The criterion previously scored programme price alone, which flattered food-pattern diets — a plan could score full marks for being free while requiring an expensive shop. Now scored as net cost above a normal food budget. South Beach 3.5 → 3.4, Dukan 2.2 → 2.0; the meal-delivery upward adjustment was retired as redundant. |
| July 2026 | User experience rewritten around clarity and daily burden; guidance added for diets with no vendor | The old anchors were written around commercial tooling, so a diet with no app scored 2 almost by default. Tools are now evidence rather than the criterion itself. Jillian Michaels 4.5 → 4.0, South Beach 2.5 → 3.5; overalls 4.2 → 4.1 and 3.4 → 3.5. The safety checklist was also amended so missing contraindications count against a plan. |
| July 2026 | Section added on medication-assisted plans | The site reviews diet plans, and programmes are increasingly bundling prescription medication with no consistent treatment in this method. Drug-free tiers are now explicitly scored on their own merits, with no deduction for what else a company sells. Tiers that require medication take a Sustainability cap of 2.0, have medication counted at the uninsured price under Cost & value, and are assessed under Safety & evidence on the quality of clinician oversight rather than on the drug itself. A standing disclosure was added for any company offering medication tiers. No existing scores change: WeightWatchers Core (3.9) requires no medication and is unaffected. |
| July 2026 | Jillian Michaels App, Cost & value 5.0 → 4.5 | Re-verified against the redefined Cost & value criterion. Pricing was confirmed unchanged at $19.99 a month or $149.99 a year, with no minimum term, no starter fee, and cancellation available any month. The subscription alone sits close to the top of the highest cost band, and the app’s meal planner is a food component — optional and configurable rather than a binding rule — which places the plan genuinely between two anchors. Overall rating unchanged at 4.1. The table above now reads live from the scoring database rather than being maintained by hand. |
| August 2026 | Medication-required tiers placed out of scope and no longer rated | The previous version of this section stated that we were not qualified to assess prescription medication, then scored medication tiers anyway — applying a Sustainability cap of 2.0, costing medication at the uninsured price, and assessing Safety on the quality of clinician oversight. That produced a rating substantially determined by a component this method disclaims competence over. We now rate food programmes only: a tier that requires prescription medication to be followed as designed is described in the review but not rated. Drug-free tiers continue to be scored normally, with no deduction for what else a company sells. No published score changes. This was verified against all five scored plans rather than assumed — none is a medication-requiring tier, and the 2.0 Sustainability cap never bound on any of them. The WeightWatchers review was separately amended to remove wording describing the retired scoring rules. |
| August 2026 | Companion nutrition programmes confirmed in scope, with a Results ceiling on medicated evidence | The scope rule adopted this month sorts tiers by whether a prescription is required. Programmes coaching people already prescribed a GLP-1 elsewhere fit neither box cleanly: they require no prescription, but their outcomes evidence reflects food coaching plus a drug. They are rated as the food programmes they are, with the restriction that medicated-population evidence cannot on its own support a Results score above 3. Without that limit, drug-driven outcomes would be credited to a food programme through Results — the side entrance the scope rule left open. No published score changes; WeightWatchers Core’s Results 4.0 was verified as resting on unmedicated trial evidence from the 2025 AJCN trial and the five-year WRAP trial. |
| August 2026 | Results split into weight-outcome and health-outcome anchors, scored by the programme’s own stated purpose | The criterion was titled “weight and health outcomes” but every anchor described weight loss only, so a pattern with strong long-term health evidence and modest scale results had no anchor that fitted. Three defensible scores could be reached from the same evidence, which breaks the half-point tolerance this method depends on. A programme marketed for weight loss is now scored on the weight anchors; an eating pattern that does not present itself as a weight-loss programme is scored on parallel health anchors, and the review states which set was used. Where weight loss is marketed at all, the weight anchors govern, so a plan cannot claim the health anchors because its weight results are weak. Weights unchanged, so no plan recalculates. All five published plans are weight-loss programmes scored on the weight anchors; none moves. |
RatingDietPlans.com is independent. We accept no payment for ratings or placement. This page is educational and is not a substitute for personalised medical or nutritional advice from a qualified healthcare professional.