Every diet that works, works by creating an energy deficit. They differ in how they get you there and in how they feel, and comparisons between them repeatedly find something inconvenient for the people selling them: which one you choose matters far less than whether you stick to it.
So the useful comparison is not on mechanism. It is on sustainability, and that is a question about you rather than about the diet.
How they actually differ
| Approach | How it creates a deficit | Suits you if | Main difficulty |
|---|---|---|---|
| Lower carbohydrate | Removes a food group, often reduces appetite | You prefer protein and fat, dislike counting | Restrictive socially, early water loss misleads |
| Lower fat | Removes the densest energy source | You prefer carbohydrate rich foods | Can be less filling without enough protein |
| Higher protein | Increases fullness, preserves muscle | Almost everyone, as an addition | Requires planning |
| Time restricted eating | Fewer hours to eat means less eaten | You dislike managing portions all day | Poor fit with family meals and shift work |
| Portion control | Eat what you eat, less of it | You want no rules about foods | Requires honest self assessment |
| Whole food focus | Less energy dense, more filling | You cook and enjoy it | Takes time and effort |
the keto diet covers one of these in detail. The pattern in that article is the pattern across all of them: real, works for the people it suits, not magic.
Why every diet looks like it works at first
Worth understanding, because it explains why testimonials for contradictory approaches can all be genuine.
Any new eating pattern disrupts habits. You stop eating on autopilot, you notice what you consume, you cut out whatever the plan excludes, and intake falls regardless of what the plan claims to be doing. Add the early water loss and the first fortnight looks impressive on any approach.
So testimonials are all describing something real and none of them are evidence for the mechanism claimed. The person who lost weight on a low carbohydrate plan and the person who lost weight on a low fat one both ate less. Their explanations differ and their outcome does not.
The questions worth asking about any plan
- What happens when it ends? If there is no answer, the answer is regain.
- Does it include enough protein? If not, more of the loss will be muscle.
- Could you eat this way at a family meal? Plans that require eating separately from everyone else have a short life.
- Does it require buying something specific? Where a product is required, the product is usually the point.
- Does it forbid whole categories without a medical reason? Restriction correlates with abandonment, and with rebound afterwards.
- Would you have chosen to eat this way anyway? The closer to yes, the higher the chance you continue.
What the comparisons consistently find
Studies putting different approaches against each other, with total energy matched, generally find similar outcomes. The DIETFITS trial in JAMA ran low fat against low carbohydrate for twelve months and found no meaningful difference between the groups, while individual results inside each group ranged all the way from large losses to gains. The variation between individuals following the same diet is larger than the variation between diets. The face is the clearest case of that: nothing directs fat loss to it, and our page on how to reduce fat from the face separates the fat from the fluid and looks at the exercises that never measured either.
The thing that separates people who succeed from people who do not, within any given approach, is how closely they followed it and for how long. That points somewhere unglamorous: pick based on what you can live with.
This is why the diet a friend succeeded on may do nothing for you. It suited their preferences and their life. The mechanism they credit is usually not the reason it worked.
The approach nobody markets
Worth naming because it never gets a book written about it: eat roughly what you eat now, somewhat less of it, with more protein and more vegetables, and keep moving.
It has no name, nothing to buy, and no mechanism to explain at a dinner party. It also performs about as well as anything else over a year, requires no elimination, and does not end, which removes the single largest cause of regain.
The reason it is not sold is that it cannot be. There is no product, no programme and no certification. That is a fact about the market rather than about the approach.
The one thing worth adding regardless
Protein, in most cases.
It helps with fullness, it preserves muscle during loss, and muscle affects both how the result looks and what you can eat afterwards. It is close to the only dietary recommendation that holds across essentially every approach.
what exercise does and does not do covers the training side of the same objective, and weight loss versus fat loss covers why muscle matters for the outcome rather than just the number.
Switching, and when it is worth it
People change approach frequently, usually at the point where progress slows, and that is generally the wrong moment.
Progress slowing after the first few weeks is normal rather than a signal that the approach failed. Switching then means restarting the adjustment period, losing the habits that were forming, and getting another satisfying fortnight of water loss that feels like proof the new approach is better. That cycle can continue for years.
The moments when switching genuinely makes sense are different: you dread the food, it does not fit your life, it is causing you to eat in ways that worry you, or you have followed it consistently for a couple of months with no change in measurements at all.
Slowing down is not stalling, and stalling for two weeks is not stalling for two months. Give any approach eight weeks of honest adherence before judging it, and judge on measurements rather than on the scale alone.
Choosing one, practically
- Start from how you already like to eat, not from what sounds most effective.
- Check it includes enough protein, and add some if not.
- Ask whether you could follow it on a holiday, at someone else’s house, and during a difficult week.
- Prefer approaches with flexibility, because rigid ones fail on contact with ordinary life.
- Give it eight weeks before judging, and judge on measurements rather than the scale alone.
What to avoid
- Anything eliminating multiple food groups without a medical reason
- Very low intakes, which produce fast loss and reliable regain, and which the NHS advises against in its own weight loss guidance
- Anything requiring a purchased product to work
- Plans with a fixed end date, since the question is what happens afterwards
- Anything you are already dreading before starting
That last one is the most reliable predictor of all. Dread on day one becomes abandonment by week six. keeping it off covers why that pattern matters more than any diet choice.
If food or your body has become something you think about constantly, or if eating feels out of control, that is worth talking to a doctor about rather than reading another article. The NIDDK sets out what supervised treatment for weight actually involves. That is not a judgement, it is just a different problem from the one this page can help with.
Frequently asked questions
Which diet is best for belly fat?
None target belly fat, because nothing does. What they do is create an energy deficit by different routes, and comparisons between them consistently find that adherence matters more than which one you chose.
Is keto better for fat loss?
It produces rapid early loss, much of which is water, and it works well for people who genuinely prefer eating that way. It is not superior once energy intake is matched, and it is restrictive, which affects how long people continue.
Does intermittent fasting work?
It works for people who find it easier to eat within a window than to moderate portions all day. That is a real advantage for some. It is not metabolically superior at matched intake, and it suits some people poorly.
What about low fat versus low carb?
Comparisons between them generally find similar outcomes when protein and total energy are matched. Which suits you is a question about preference and satiety rather than about which is theoretically correct.
Do I need to cut out sugar entirely?
Reducing sugary drinks and snacks helps because they are energy dense and not filling. Total elimination is rarely necessary and often backfires, since approaches with no flexibility tend to be abandoned.
So which should I pick?
The one closest to how you would like to eat anyway, that includes enough protein, and that you could imagine continuing indefinitely. That is not a compromise answer, it is what the comparisons actually support.
This article is general information, not medical advice, and is not a substitute for care from a qualified healthcare professional. Speak to your doctor about your own situation.
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