application_controller.rb

def object_changed?(instance, params)
  instance.attributes != instance.attributes.merge(params)
end

controller.rb

def update
    unless object_changed?(@account, accounts_params)
      redirect_to accounts_path, notice: "There were no changes to be made."
      return
    end

    if @account.update(accounts_params)
      redirect_to accounts_path, notice: "Account updated."
    else
      flash.now[:error] = "Account could not be updated."
      render action: :edit
    end
  end