Feb 06, 2021 / by Jon Bellis / No Comments

In this post, we provide a personal trainer’s guide to food, diets and nutrition. How can we make recommendations to suit everyone? After all, every one of our private training clients is distinct; their drivers are all different, their ‘why’ is unique. But when we turn their vision into a plan, we can distil their aspiration into one of a small number of common goals.

That’s handy, because it means we can apply a set of rules to provide them with nutrition advice and an eating plan. It also means we can share that information with you and be confident that it is sound advice.

Below we list the common goals and the nutrition rules-of-thumb that apply to each. But first, what are the rules-of-thumb when it comes to food?


Nutrition rules-of-thumb

Here is a list of sound pieces of advice.


Eat lots of good carbs and fibre

Hidden in this category is some common advice; you’ll recognise it in the subheadings. But first, what are good carbs?

Good carbs are carbohydrate sources that digest slowly. All carbs release sugar into the bloodstream, but some release it rapidly and others much more slowly. If you only ever consume fast-digesting carbs, you’re heading for health issues, including low energy, low mood and metabolic diseases such as diabetes. If you eat unrefined, slow-digesting carbs, you’ll benefit from better physical and mental health.

Fibre is equally essential. It will help food digest slowly and provide your microbiome with lots of fuel and nutrients. A healthy microbiome will serve you well, providing many useful services and health-giving nutrients.

So, what foods contain good carbs and fibre?


Fruit and veg

All fruit and veg contain carbs. Some have a little protein, and others contain some fat. But mostly, they are a great source of carbs and fibre. Make sure you get plenty of variety. I include relatively high carb vegetables such as potatoes and sweet potatoes in this bucket.


Lots of fibre - fruit, veg, wholegrains. A personal trainer's guide to food, diets and nutrition

Whole grains

Grains are a traditional source of carbs. Think breakfast cereals, bread, pasta, cake. The problem with those foods is that they are highly refined and processed. That makes them fast digesting. Instead, choose whole grains that have had minimal processing. There are plenty to choose from: whole versions of wheat, oats, rice, barley, maize, spelt, buckwheat, millet, rye, quinoa.

Whole grains don’t just provide carbs. They are packed with fibre and nutrients.



In common with fruit, veg and whole grains, legumes have plenty of slow-digesting carbs and fibre. But legumes often have reasonable amounts of protein too, so they work well for vegetarians and vegans as a protein source. Any type of bean, chickpeas, lentils and peas would fit into this category.


Get enough protein

Protein provides the building blocks for muscles and other structural tissues and is vital for hormones and nutrient transport.

Fitness magazines that contain adverts for protein supplements would have you believe you need lots of protein. You don’t need lots, but you do need enough. What is enough? Well, that depends on you and your goal. Read on to find out more detail.

Almost all products derived from animals contain good amounts of protein, and there are plenty of plant sources such as legumes, whole grains, nuts and seeds.


Ensure you get all the essential amino acids (EAAs)

Amino acids are the building blocks of protein. Some you can synthesise, but others you have to provide in your diet; they are called essential amino acids. Most vegetable protein contains inadequate amounts of some EAAs. That makes those protein sources much less useful for enabling the variety of functions required to keep us healthy.

Isn’t this sort of the same as protein? Not quite. Protein appears separately to EAAs because it relates to satiation and overall protein amounts, whereas EAAs are listed to cover essential bodily functions – in short, health.

All animal proteins contain all the EAAs and are termed ‘complete’. Most plant proteins are incomplete, with some notable exceptions such as quinoa, soya beans and peas. But, otherwise, as long as you get plenty of variety of whole grains, legumes, nuts, seeds and vegetables, you should be getting your EAAs.


Ensure you get enough essential fatty acids

Fatty acids are the building blocks of fats. Your body can make most types of fatty acids, but those it cannot are termed essential. Primarily, we’re talking about omega 3, 6 and 9. Omega 6 is generally plentiful in the western diet due to the prevalence of sunflower oil in foods. The best source of omega 3 is oily fish, but there are also good plant sources such as green leafy vegetables and flaxseed.

A close up of a salmon fillet. A personal trainer's guide to food, diets and nutrition


Include some low-fat dairy

Low-fat dairy is included as an excellent source of calcium. As you’ll see, calcium is essential for many bodily functions, but is especially relevant for muscle contraction and weight loss. It’s also one of the recommendations on the government’s Eatwell plate.


Supplement with vitamin D

It’s not a food as such, but it is essential. It’s included because most UK people are deficient in vitamin D in the winter, due to a lack of sun exposure. What’s more, there are very few foods that contain any appreciable amounts. So this is a recommendation for supplementation of vitamin D.

Vitamin D is involved in systems such as bone health, immunity and hormone regulation, to name a few.


Cut right back on bad carbs

As we discussed earlier, bad carbs are carbohydrate sources that digest quickly. They tend to come from refined grains or confectionery. Examples would be breakfast cereals, cereal bars, bread, pasta, white rice, pastries, crackers, muffins, cake, sweets and sugary drinks.

These provide very few healthy nutrients and, when consumed habitually, will lead to metabolic disease.


Minimise processed foods

Refined foods tend to have few healthy nutrients and a lot of additives. Processed meat has been associated with cancer, but any food with a long list of unfamiliar ingredients tends to be highly processed and may be detrimental to your health. Examples might be pot noodles, some ready meals, biscuits, crunchy snacks, cake, commercial bread and confectionery.


Reduce saturated fat

Your body can make saturated fat, so it’s therefore non-essential. Excess dietary saturated fat has been associated with coronary heart disease and degenerative brain disorders.


Minimise alcohol intake

Many people use alcohol as a de-stressor but, ultimately, it will increase stress hormones and lower your mood. It has no beneficial place in any health, wellbeing or fitness programme.

Bottles of beer chilling in an ice bucket


Reduce caffeine intake

You can become dependent on caffeine to lift your mood and energy levels. But too much caffeine will make you low during caffeine breaks. It’s easy to keep increasing your dose as you seek alertness and positivity against a backdrop of reduced neural activity caused by excess caffeine.


Achieve the right calorie balance

If you’re trying to lose weight, a calorie deficit is essential. If you’re trying to gain weight, a calorie surplus is necessary. If your primary goals are not about weight, then calorie parity may be appropriate.


Goal to food mappings

In the last section, we presented the list of diet-related recommendations. Now let’s apply them to the various goals of personal training clients.

This table lists common goals across the top and the diet-related recommendations down the side. A ‘Y’ indicates that the recommendation is important for that goal. An ‘N’ means it’s detrimental to that goal and a grey square means it’s neither good nor bad. Below, we explain each entry.

A simple food mapping illustrating a personal trainer's guide to food, diets and nutrition

Goal: Improve health

The best thing you can do for health is to consume a varied and balanced diet free from refined foods, bad carbs and alcohol, and minimise saturated fat and caffeine.


Fruit and veg

A large variety of fruit and veg will ensure you get all the different nutrients required for optimal health. Nutrients will improve the way your body functions, making you feel well. Vitamins and minerals are essential for brain health, helping to prevent mental illness. You’ll also get good carbs and fibre. Carbs are vital fuel for active muscles and the brain. And fibre will keep your microbiome healthy, which will contribute even further to good health and prevent gut-related disease.

Whole grains and legumes also provide good carbs, fibre and even more nutrients. A wide variety of fruit, veg, whole grains and legumes will provide huge mental and physical health benefits.

A close up of some beans, some variegated.



Getting enough protein is critical for good health. If you get too little, your body will scavenge muscle, and you’ll waste. Ultimately your organs will not function correctly, and you’ll feel unwell and become diseased. Currently, government recommendations are 0.75g per kg of bodyweight. You may need more than that, depending on your lifestyle and other goals, but this should be your starting point.


Essential amino acids

If you consume animal protein, then you’ll be getting all the EAAs. If not, then you’ll need to understand your plant-based protein sources in terms of amino acid content. If that’s too much to think about, ensure you get a variety of good carbs from whole grains, legumes, vegetables, nuts and seeds.


Essential fatty acids

Your brain is 60% fat and essential fatty acids make up a significant proportion of that. Research has shown that an equal supply of omega 3 and omega 6 helps keep the brain healthy, can reduce the risk of mental health issues and may help prevent disease. The best sources are oily fish and vegetable oils. If you don’t eat fish, then you can get your omega 3 from flaxseed, walnuts, nuts, seeds, and soybean oil are good sources.


Low-fat dairy

Low-fat dairy is an excellent source of calcium, which will help to keep your bones and teeth healthy. But it’s also involved in many cellular processes, so if you want optimal health and energy levels, ensure you consume a good source of calcium. If you are plant-based, you can get calcium from green leafy vegetables, tofu, sesame seeds and pulses.


Vitamin D

Vitamin D works with calcium to keep bones strong. But it’s also an essential contributor to the processes involved in immunity and hormone production. Without it, your immune system will be compromised, and you may end up with low testosterone. One contributing factor to increased incidences of colds and flu in the winter is vitamin D deficiency.


Refined carbs

Refined fast-digesting grains, when eaten habitually, will desensitise your cells to insulin. That means you may end up with high blood sugar and experience all the negative consequences of that or, ultimately, type 2 diabetes. Sugar highs and lows can also lead to poor eating behaviours, with low blood sugar-induced ravenous hunger preceding a bad carb binge. Then followed a little later by the next blood sugar low and bad carb binge. And so the cycle continues.


Refined foods

Refined foods provide few nutrients and may be detrimental to your health and mental wellbeing. Processed meat, in particular, is associated with cancer. What processing and additive related cancer associations will they uncover next?


Saturated fat

Excess saturated fat is unequivocally associated with higher cases of coronary heart disease. It’s also a known factor in the development of Alzheimer’s. It’s not an essential nutrient because you can make it. You won’t be able to eliminate it, because it’s in many everyday healthy foods, but you should aim to reduce it as much as possible and have foods like cheese on rare occasions.

A close up of yellow holey cheese. A personal trainer's guide to food, diets and nutrition



It’s not the alcohol in red wine that conveys health benefits; it’s the polyphenols. You can get polyphenols from other foods – like grapes! Alcohol will affect your blood sugar control, lower your testosterone, increase cortisol, make you hungry, reduce your self-control and disturb your sleep. It’s also, technically, a toxin. You’ll feel better if you can be alcohol-free, but certainly you should aim to be well below the government’s 14-unit safe intake level.



Habitual excess caffeine will downregulate neurotransmitter activity in your brain. That means when you have a caffeine break, you’ll feel low: low energy, low mood. You’ll reach for more caffeine to fix this, and so the vicious cycle continues. Aim to reduce your intake to one or two cups of tea or coffee per day, or go caffeine-free.


Calorie balance

Being in calorie balance is the healthiest option, providing you are not overweight. If you are overweight, lower your calorie intake a little below maintenance until you achieve a healthy weight and then stabilise. If you consume too few calories that will affect your hormones, muscle mass, mood and, probably, health if your food choices do not provide all the nutrients you need.


Goal: weight loss


Calorie balance

First and foremost, you need a calorie deficit if you want to lose weight. It’s fundamental. You must burn more energy than you consume. But, too much of a deficit will be detrimental. A slow and steady pace is a lot healthier and will give you better end results, so we recommend a deficit of around 500 calories per day.

There are an enormous number of special diets for losing weight. If you follow the advice in this article, you shouldn’t need anything faddy or restrictive. For example, a keto diet may appear to work in the short term, but it has no proven long-term efficacy. And it’s fundamentally unhealthy.

The only time you may want to personalise the advice in this article is if you’re going to practise intermittent fasting. But even in this case, the food advice is the same; it’s just the timings that are unconventional.


Good carbs

Good carbs and fibre are essential for healthy weight loss. They will fill you up and keep you full for longer. That’s essential if you are in a calorie deficit. If you eat faster-digesting carbs, you are more likely to get hungry and fail to stick to your calorie allowance. You’re also more likely to get ‘hangry’.



Protein is essential for two reasons. First, it is satiating, so will help to keep you feeling full. Second, when you are in a calorie deficit, a little more protein will help protect muscle tissue from being used for other processes and energy. Protein also has a considerable energy cost of digestion, which means you ultimately receive fewer calories.  We recommend to our client a protein intake significantly above the government recommendations for these reasons. In theory, it’s not necessary. In practice, you’re more likely to get better results.


Low-fat dairy

Research has shown that calcium has a positive effect on weight loss, and studies have shown that consumption of low-fat dairy facilitates better weight loss in study subjects.


Vitamin D

Vitamin D is vital for testosterone production. Testosterone is great for body composition changes and energy levels meaning, ultimately, it’s going to help you get rid of fat, build muscle, burn more calories and feel energetic.


Bad carbs

Bad carbs will significantly affect your ability to lose weight. Not only will increased insulin levels blunt fat burning, but you may experience a lot more hunger and be unable to stick to the plan.



Alcohol will blunt testosterone, increase cortisol and contribute a lot of calories. Habitual consumption will sabotage your attempts to lose weight. You’ll do a lot better with your weight loss if you cut it out altogether. If that’s impractical, then keep it to 3 or 4 drinks a week or below.


Goal: gain muscle


Good carbs

If you’re trying to gain muscle, then good carbs will trump bad carbs in most situations. Good carbs will give you greater energy levels and better testosterone production. Carbs are also anabolic because they improve the energy status of muscle cells and cause cell swelling, both of which help to promote muscle protein synthesis. DOn’t be tempted to go low carb if you want to build muscle.

Good carbs will also convey health benefits for better overall functioning of the physiological processes required for gaining muscle.

The only exception to this good carb rule is after a workout, where fast-digesting carbs may enable you to start the recovery process sooner. But even that is debatable.



Adequate protein is essential for gaining muscle, especially if you’re creating high levels of fatigue in your workouts. Many recreational weight lifters consume too much, influenced by the magazines and their muscular role models sponsored by protein companies.

Research has suggested that you will not need more than 1g of protein per pound of lean bodyweight. Beyond that, you will simply excrete the excess nitrogen.


Essential amino acids

Animal protein will help you achieve the best results without too much thought, as it contains all the EAAs. But even if you are vegan, you can still enjoy the same gains by making the right food choices and combining protein sources to get all the EAAs.


Low-fat dairy

At the molecular level, calcium is an integral part of the chemistry of muscle contraction. If you want strong muscle contractions to stimulate growth, you need a source of calcium. Low-fat dairy or plant sources of calcium will give you the calcium you need for muscle contraction.

Greek yoghurt with strawberry and blueberries on top


Vitamin D

If you want to gain muscle, you need testosterone. Vitamin D supplementation will help maintain healthy testosterone levels, especially in the winter.



You’ll notice that caffeine is rated as neither good nor bad. More accurately, it’s both good and bad. Caffeine can help energise you for a workout, but a lot of recreational lifters get far too much caffeine, usually in the form of a commercial pre-workout drink. These drinks can contain as much as 300mg of caffeine. For reference, a standard cup of coffee contains around 50mg. You can get a perfectly good workout without caffeine. If you need caffeine as a pick-me-up, it’s probably because you’re in a slump caused by a caffeine-induced reduction in neurotransmitter activity.

My advice would be to cut caffeine consumption, say, to two cups of tea or coffee per day. If you want to use one of those as a pre-workout boost, that would work well.

Steaming coffee and beans


Calorie balance

If you want to gain appreciable amounts of muscle, you will need to be in calorie surplus. You can gain small amounts of muscle while in calorie balance, or even deficit. But if your main goal is muscle size and strength gains, then a surplus is recommended. Start with 250g per day and monitor body fat accumulation. Only take it up if your gains slow and you’re not getting fat.


Goal: sport-specific

The goal of sport-specific training is to maximise performance. In most cases, this means increasing your power to weight ratio. You want to be strong and lean for almost all sports. There are some exceptions, such as rugby and American football, where bulk is helpful, but generally you’ll want to build strength and reduce body fat. That means eating for sport training has the same discussion points as weight loss and muscle gain. At least in terms of training.

But for competition, it’s different.

Ahead of the competition event, be that a match, game or show, for example, the nutrition for preparation and training will follow the guidelines above. But for the 24 hours around the event you may need to change things a little. For example, you may want to reduce your fibre intake. You don’t want to be too bloated when you need maximum performance, speed and agility. Because we’re only talking about a few hours around the event, there’s no real requirement for any of the recommendations above. And, to some extent, competition eating is a matter of preference.

You may want to stick to slow-digesting carbs ahead of the event, but cut down on fruit, veg and legumes to reduce bulk. You should also avoid heavy, greasy meals beforehand. Or you may like to have an isotonic sports drink during the event, and you may also want fast-acting carbs and protein after the event. Aside from that, it would be difficult to make more specific recommendations because every individual and every sport is different. Competition prep is a very personal issue.



We’ve provided a personal trainer’s guide to food, diets and nutrition. Our advice isn’t complicated because the recommendations are pretty much the same regardless of goal or current status.

It’s simple:


  • Fruit and veg
  • Whole grains
  • Legumes
  • Adequate protein, including all the essential amino acids
  • Essential fatty acids
  • Low-fat dairy
  • A vitamin D supplement

Avoid or reduce:

  • Fast-acting carbohydrate
  • Refined foods
  • Saturated fat
  • Alcohol
  • Caffeine

Choose the right calorie balance.

And we almost forgot! Drink plenty of water – this habit will undoubtedly improve your goal attainment.

This strategy is at the heart of the nutrition advice we give our personal training clients here at our private studio in Northampton. However, we tailor a diet plan based on their personal preferences and family routines. Knowing the rules of thumb is one thing, but turning that into meals is another. It requires practice, but it’s worth it for life long health and fitness.

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