Weight Loss Diet: Complete Guide

What is a weight loss diet?

A weight loss diet (or fat loss diet) is an eating pattern that supports losing body fat by creating a calorie deficit: you eat fewer calories than your body uses each day. Over time, the body draws on stored fat for energy, so you lose weight. The best diet to lose weight in studies is not one specific plan but whatever helps you consistently eat less while staying nourished and satisfied. That might be a balanced diet, a healthy diet based on whole foods, or a named pattern such as the Mediterranean, DASH, or low-carb diet–all can work when combined with a deficit.

There is no official “weight loss diet plan for women” or “weight loss diet plan for men” that is universally best; needs vary by age, activity, and health. A diet plan for weight loss can be a 7 day diet plan for weight loss, a healthy diet meal plan, or a simple diet plan for weight loss you build yourself. Diet programs and diet plans from reputable sources (e.g. NHS, NIH) often provide healthy diet plans or a free diet plan for weight loss that you can adapt with a TDEE calculator.

Core principles

• Eat in a calorie deficit (fewer calories than you burn) for fat loss.
• Prioritise diet food that is filling and nutritious: vegetables, fruits, lean protein, whole grains, legumes, healthy fats.
• Limit highly processed foods, added sugar, and sugary drinks.
• Choose a pattern you can sustain–the best diet plan is one you stick to.

How a weight loss diet works

Weight loss happens when energy intake is lower than energy expenditure. Your TDEE (total daily energy expenditure) is the calories you burn in a day; if you eat less than that, you are in a deficit. A modest deficit (e.g. 300–500 kcal per day) typically leads to about 0.5–1 kg (1–2 lb) loss per week–a sustainable rate. A quick weight loss diet or rapid weight loss diet that cuts calories too sharply may cause muscle loss, fatigue, and rebound gain; a healthy diet to lose weight focuses on steady, sustainable change.

There are no mandatory phases. You can start with a diet plan to reduce weight that fits your life: for example, a diet food plan or menu diet with set diet meals and diet breakfast ideas, or a diet and exercise plan for weight loss. The best diet for fat loss and best diet for belly fat (or diet to lose belly fat) is still any approach that creates a sustained deficit–you cannot spot-reduce fat, but overall fat loss will include the belly over time.

What to eat and what to limit on a weight loss diet

Best diet foods and healthy diet foods are those that are filling, nutrient-dense, and relatively lower in calories for the volume you eat. The table below summarises good diet foods and what to limit. Diet food for weight loss and diet recipes that you enjoy make it easier to stick to your diet plan for weight loss.

Building diet meals around protein and vegetables helps with fullness. Diet breakfast ideas include eggs with vegetables, oatmeal with fruit, or yogurt with nuts. For diet recipes and best diet meals, look for healthy diet options that use whole foods–similar to a balanced diet food list or whole food diet approach. A high fiber diet or high fiber diet plan can also support satiety. Avoid relying on diet shakes, diet drinks, or protein shake diet as your main strategy unless advised by a dietitian; real food is usually more sustainable.

Potential benefits of a healthy weight loss diet

When done in a sustainable way, a healthy diet plan for weight loss may support:

• Fat loss: A consistent fat loss diet or fat loss diet plan that creates a moderate calorie deficit can reduce body fat and improve body composition over time.
• Metabolic health: Losing excess weight may improve blood sugar, cholesterol, and blood pressure in some people. An insulin resistance diet or diet for weight loss for female or male with metabolic concerns should be individualised with a doctor or dietitian.
• Habit building: A healthy diet to lose weight or easy diet plan for weight loss that you can maintain helps form lasting habits rather than short-term restriction.

Quality of evidence: weight loss from a calorie deficit is well established; the “best diet” is the one that achieves that deficit in a way you can sustain. Talk to your doctor about whether a weight loss diet is appropriate for you and what rate of loss is safe.

Risks and who should be cautious

Crash diets and rapid weight loss diet or best diet for fast weight loss plans that promise quick results often restrict calories too much. They can lead to muscle loss, nutrient deficiencies, fatigue, and rebound weight gain. A quick weight loss diet plan or fast weight loss diet plan is rarely sustainable or safe without medical supervision.

Who should be cautious:

• People with a history of eating disorders–strict diet plans can trigger relapse.
• Pregnant or breastfeeding women–weight loss diets are generally not recommended unless advised by a doctor.
• People with diabetes, heart disease, or kidney disease–diet changes can affect medications and conditions; supervision is important.

Before starting any weight loss diet plan, especially a diet to lose weight and gain muscle or body recomposition diet, consult your doctor or a registered dietitian. Use our calorie calculator and TDEE calculator to set realistic targets.

Sample weight loss diet day (meal ideas)

This is one example of diet meals for a weight loss diet–not a prescriptive plan. Adjust portions to your calorie target (use a calorie deficit calculator to find yours).

• Breakfast (diet breakfast): Scrambled eggs with spinach and whole-grain toast; or oatmeal with banana and a handful of nuts; or Greek yogurt with berries (healthy diet breakfast options).
• Lunch: Large salad with grilled chicken, chickpeas, and olive oil dressing; or vegetable soup with a whole-grain roll and an apple.
• Dinner: Baked fish or chicken with roasted vegetables and a small portion of brown rice or quinoa; or a bean-based chilli with a side salad.
• Snacks (diet snacks): Fruit, raw vegetables, a small handful of nuts, or plain yogurt. Best diet snacks are filling and moderate in calories.

For more structure, use a 7 day diet plan for weight loss, diet meal plans, or healthy diet meal plan from a reputable source or dietitian. Diet recipes and diet food ideas that fit your tastes make the plan easier to follow. You can also explore our guides to the calorie deficit diet, Mediterranean diet, or low-carb diet as templates.

Frequently asked questions about weight loss diets

Summary

A weight loss diet works by creating a calorie deficit with a pattern you can sustain. The best diet to lose weight is one that fits your life–often a healthy diet plan for weight loss with plenty of vegetables, lean protein, and whole grains. Use a diet plan for weight loss or diet meal plans as a template and tailor them with our calorie calculator, TDEE calculator, and calorie deficit calculator. Avoid crash diets and rapid weight loss diet promises; aim for steady, sustainable loss. Before starting, talk to your doctor or a dietitian. For specific patterns, see our guides to the calorie deficit diet, Mediterranean diet, low-carb diet, or DASH diet.

Use our calculators with this diet

Set your calorie target and plan meals with our free tools.

Sources and further reading

This article is based on current scientific and clinical sources. For more detail, see:

• NIH / NIDDK: Weight management and healthy eating
• NHS: Weight loss – get started
• Cochrane and systematic reviews on diet and weight loss (comparison of named diets)
• National guidelines on obesity management and dietary patterns

Last updated: 20 February 2026. Content is for educational purposes only and does not replace medical advice.