Your PT Sees You Once a Week. Your Diet Happens Every Day.

A PT session is an hour. Maybe two hours a week if you are consistent, and most of my clients with jobs and kids are not consistent every single week. Meanwhile you eat every day of that week. Breakfast at the kopitiam, lunch from the food court downstairs, dinner at home or not at home, plus whatever happens at 11pm when the day has been long.

That is the whole tension in one paragraph, and it is why people ask me whether they should be paying for a trainer or for nutrition coaching. I want to answer it properly, which means starting with what I am not going to tell you.

I am not giving you a percentage

You have seen the line. Results are 80 percent diet and 20 percent training. Or 70/30. Or 90/10, depending on who is selling.

I went looking for where that ratio comes from. It does not come from anywhere. There is no study that partitions weight loss into a diet share and a training share and lands on a number. It is a slogan that got repeated until it sounded like a finding. So I am not going to print one, and if a coach quotes you a ratio with a straight face, ask them for the paper.

What I can do is show you what has actually been measured about contact, coaching and training, and let you draw the line yourself.

What coaching contact is worth, measured properly

The most useful trial I know on this randomised 437 people who were already on an online weight loss programme and were not losing much after the first month. One group carried on with no coaching calls. One group got three weekly coaching calls. One group got twelve.

At four months, the twelve call group had lost 7.0 percent of their body weight, the three call group 6.2 percent, and the no call group 4.5 percent. At twelve months it was 5.5, 4.9 and 3.9 percent (Unick et al., 2024). The proportion hitting a 5 percent loss at four months was 65.9 percent with twelve calls, 58.5 percent with three, and 36.5 percent with none.

Two honest readings of that.

The first is that having a human in the loop clearly beat having nobody. The gap between some coaching and no coaching is the big one in that data.

The second is the one a coach is not supposed to say out loud: three calls captured most of the benefit of twelve. Four times the contact did not produce four times the result, or anything close to it. If you are choosing between a heavily supervised package and a lighter one, that finding is on your side, not mine.

The active ingredient looks like accountability

There is a neat illustration of this in the research on stepping on the scale. A meta-analysis of self-weighing trials found that weighing yourself on its own produced a loss of about half a kilogram, with a confidence interval that crossed zero. In plain English, on its own it did nothing reliable. Put the same scale inside a proper behavioural programme and it was worth about 1.7 kg.

The detail I keep coming back to is this one: trials where people had to report their weight to somebody averaged 3.6 kg, against 2.3 kg where they did not, and that difference was statistically significant (Madigan et al., 2015). Same scale. Same numbers on it. The variable that moved the result was whether anybody else was going to see them.

You can see the same shape in a large trial that put 811 adults on four different macronutrient combinations for two years. The diets ended up statistically indistinguishable. What did predict how much people lost was how many group sessions they turned up to, at roughly 0.2 kg per session attended (Sacks et al., 2009). And a network meta-analysis of 48 trials across 7,286 people found the branded diets landed in the same place as each other, with the authors concluding that this supports recommending any diet a person will actually adhere to (Johnston et al., 2014).

Attendance. Adherence. Somebody watching. That is the thread running through all of it, and none of those things happen inside the sixty minutes you are on the gym floor with me.

So what is the training actually for?

This is where I want to be careful, because “diet matters more” gets twisted into “training is pointless” and that is wrong.

The American College of Sports Medicine’s position stand on physical activity and weight is direct about it. Resistance training does not enhance weight loss, but it may increase fat-free mass and increase the loss of fat mass (Donnelly et al., Medicine and Science in Sports and Exercise, 2009). Read that as a job description rather than a demotion. Lifting is not primarily how you move the number on the scale. It is how you change what you are made of while that number moves.

The same position stand puts the activity volumes needed to shift weight through movement alone at 150 to 250 minutes a week to prevent weight gain and produce modest loss, and above 250 minutes a week for clinically significant loss and better maintenance. That is a lot of hours. It is achievable for some people and completely unrealistic for a dad doing shift work with a two year old at home.

There is also a limit built into us. Research using doubly labelled water across 332 adults found that total daily energy expenditure tends to plateau at higher activity levels rather than climbing in a straight line, which is one reason the “just train it off” plan disappoints so many people (Pontzer et al., Current Biology, 2016).

How I put the two together

My honest position, as a coach rather than as a citation:

• Training is what you do. Nutrition is what you keep doing. Your session is a scheduled event with a coach standing there. Your eating is 21 unsupervised decisions a week, made tired, made in a hurry, made in a queue at the food court.
• Buy the accountability, not the hour. The evidence points at contact and reporting as the lever, not at intensity of supervision. Even modest, regular contact beat none by a wide margin.
• Do not over-buy. Twelve calls beat three by a little. Three beat zero by a lot. If your budget is tight, the cheaper end of that curve is where most of the value sits.
• Keep lifting anyway. Not for the scale. For what is underneath it, and for everything training does for you that has nothing to do with body weight.
• Track something, often. A study of 142 people found that how frequently people logged their food predicted weight loss, while how much time they spent logging did not (Harvey et al., 2019). Short and regular wins.

If you can only afford one thing right now, buy the one that touches the other six days. If you can afford both, use the PT hour to build the skill and the strength, and use the coaching to survive Tuesday.

And the standard caveat, which I mean sincerely: if you have a medical condition, are on medication, or have not been active in a long time, talk to your doctor before you change your training or your diet. Nothing here is medical advice.