WEIGHT MANAGEMENT ∙ 6 minute read

The fundamentals of nutrition and weight loss

By Dr Leah Gorodi

The aim of a healthy diet is to achieve a balance of all major food groups in the right proportions and to eat ‘nutrient-dense food’. Generally speaking, this means focusing on a varied diet, which is mostly plant-based and minimally processed.

Nutrient-dense foods are defined as foods that contain high amounts of nutrients per calorie. Top contenders include vegetables, fungi (mushrooms), herbs and spices, fruits, legumes, whole grains, nuts and seeds, with animal food sources following this (eggs, poultry, and red meat). ‘Empty calorie’ foods usually contain high fat, sugary, or highly processed products - these include processed meats, fried foods, high-fat dairy products, and sugar-sweetened drinks.

While there is no superior single dietary approach, you should work towards a healthy, balanced diet rich in fruit and vegetables. You should also optimise your water, caffeine, and alcohol intake, as well as eat within a calorie deficit to help you reach your goals.

Macro and micronutrients

You may have come across the terms macro and micronutrients before. Macronutrients are nutrients we need in large amounts to provide our energy requirements which include protein, fats and carbohydrates (including fibre). Micronutrients are all the vitamins and minerals that we need in very small amounts - they have high amounts of antioxidant and anti-inflammatory properties. Inflammation in the body is thought to underpin many underlying disease processes. 

Each type of food has both a macro and micronutrient profile, which is why foods are all so different in colour, texture, and taste. It’s really important to eat a high variety of different foods - which we call ‘a rainbow diet’ - getting many different colours on your plate means you’re likely to gain all the nutrients that your body needs. 

Whole foods and processed foods

Generally speaking, the more whole the food (closest to its natural form), the more nutritious it is. At each step of processing food, some of its nutritional value is lost - this is why ultra-processed foods are usually very unhealthy. Adding to this, highly processed foods usually have added ingredients like salt, sugar, chemicals, sweeteners and preservatives that are not good for you. 

Minimally processed foods are food products that have had something done to it but nothing has been added - this could be due to a process such as freezing, drying, or boiling. 

If you want to be able to tell if a food is highly processed, look at the food label - if there is a long list of ingredients and things that you do not recognise, it is likely to be highly processed. Cooking meals yourself from scratch is the surest way to avoid processed food products and sticking to a whole-food diet. 

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The benefits of a plant-based diet

Research has shown that plant-based foods have significant additional health benefits and are superior in their nutritional profile. They contain high amounts of a natural compound called phytonutrients and studies have shown it may protect against several chronic diseases including cancer. 

A mostly plant-based diet is also naturally lower in saturated fat: this helps lower the risk of obesity, type 2 diabetes, stroke, and heart disease by lowering cholesterol levels. Studies have also shown that increasing your plant intake can help reduce the risk of dementia and generally may even help you live longer.

This doesn’t mean you need to exclude all animal food sources from your diet, but generally speaking, you should try to replace some of your meat and dairy intake with plant-based alternatives to gain nutritional benefits from them.

Food preparation

In order to eat healthily, it’s also important to focus on the way you prepare your food. You should ensure you use a small amount of healthy cooking oil (e.g. unsaturated fats such as olive oil and rapeseed oil). If you are frying, you could try a cooking oil spray to control the quantity used. Another good option is to cook in liquid rather than oil (e.g. water or stock). 

Healthier cooking methods include boiling, braising, steaming, grilling, and microwaving. The best way to retain the most nutrients in vegetables is to avoid overcooking - steaming, stir-frying, and lightly boiling better preserves water-soluble vitamins. Try to keep the skin on some vegetables (e.g. potatoes) - this will mean you consume higher amounts of fibre too.

Calories and calorie restriction

It’s really important when thinking about weight loss and weight maintenance to consider your calorie intake and portion sizes. You can be eating lots of healthy food, but if it’s too much, you won’t be able to achieve the results you want. 

The amount of energy in an item of food or drink is measured in calories. If we take in more than we need, we will gain excess weight by storing it as fat. To maintain a stable weight, the amount of energy we put in our bodies needs to match the amount of energy we use up - this will be affected by everything that we do such as moving, sleeping, and even breathing - as well as exercise. 

In order for you to lose weight, your body needs to be in a calorie deficit, which means taking in less than you need so that your body will use up the excess fat you have stored in your body. 


Making sure you stay hydrated is extremely important for maintaining a balanced diet, optimising your health, and aiding weight loss. Try to drink at least 6-8 cups of water per day, which is around 1.5-2 litres. All drinks count, including tea, coffee, and juices; however these will almost always contain extra calories and possibly sugar, so you need to be aware of this when you are making your drink choices and stick to mostly water. 

The current recommended safe drinking level of alcohol is less than 14 units per week for both men and women. Drinking regularly above this has widespread health effects. Alcoholic drinks are full of ‘empty calories’ which have no nutritional value and are usually high in sugar. As a result, drinking too much alcohol regularly can cause weight gain which can lead to heart disease, stroke, and type 2 diabetes. It is also associated with other serious health conditions including liver disease and seven different types of cancer.

The numan take

Focusing on nutrition is fundamental to achieving your weight loss goals, and should be considered alongside exercise, mindset, and sleep to help you on your journey towards a healthier you. While it is an essential element of weight loss, it is multi-faceted and it can be difficult to know where to start. For more advice, the NHS has a good ‘eatwell’ guide which is suitable for most adults. It’s a useful resource for an idea of portion sizes and food types, but keep in mind that you may need more specific diet advice if you have a particular health condition.